diff --git a/_codeql_detected_source_root b/_codeql_detected_source_root
new file mode 120000
index 0000000..945c9b4
--- /dev/null
+++ b/_codeql_detected_source_root
@@ -0,0 +1 @@
+.
\ No newline at end of file
diff --git a/c/src/supermarket.c b/c/src/supermarket.c
index 414ce1d..12b432c 100644
--- a/c/src/supermarket.c
+++ b/c/src/supermarket.c
@@ -3,6 +3,19 @@
 #include <stdio.h>
 #include "supermarket.h"
 
+// Constants for magic numbers
+#define DEFAULT_ITEM_QUANTITY 1.0
+#define TWO_FOR_AMOUNT_QUANTITY 2
+#define THREE_FOR_TWO_QUANTITY 3
+#define FIVE_FOR_AMOUNT_QUANTITY 5
+#define PERCENTAGE_DIVISOR 100.0
+
+// Constants for discount description strings
+#define THREE_FOR_TWO_DESCRIPTION "3 for 2"
+#define TWO_FOR_FORMAT "2 for %f"
+#define FOR_FORMAT "%d for %f"
+#define PERCENT_OFF_FORMAT "%.0f%% off"
+
 struct product_t* product_create(char* name, enum unit unit) {
     struct product_t* product = malloc(sizeof(*product));
     strncpy(product->name, name, sizeof(product->name) - 1);
@@ -76,36 +89,36 @@ void handle_offers(struct cart_t* cart, struct receipt_t* receipt, struct specia
             int x = 1;
 
             if (offer->type == ThreeForTwo) {
-                x = 3;
+                x = THREE_FOR_TWO_QUANTITY;
             } else if (offer->type == TwoForAmount) {
-                x = 2;
-                if (quantityAsInt >= 2) {
-                    double total = offer->argument * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
+                x = TWO_FOR_AMOUNT_QUANTITY;
+                if (quantityAsInt >= TWO_FOR_AMOUNT_QUANTITY) {
+                    double total = offer->argument * (quantityAsInt / x) + quantityAsInt % TWO_FOR_AMOUNT_QUANTITY * unitPrice;
                     double discountN = unitPrice * quantity - total;
                     char description[MAX_NAME_LENGTH];
-                    sprintf(description, "2 for %f", offer->argument);
+                    sprintf(description, TWO_FOR_FORMAT, offer->argument);
                     discount = discount_create(description, -discountN, &product);
                 }
             } if (offer->type == FiveForAmount) {
-                x = 5;
+                x = FIVE_FOR_AMOUNT_QUANTITY;
             }
             int numberOfXs = quantityAsInt / x;
-            if (offer->type == ThreeForTwo && quantityAsInt > 2) {
-                double discountAmount = quantity * unitPrice - ((numberOfXs * 2 * unitPrice) + quantityAsInt % 3 * unitPrice);
+            if (offer->type == ThreeForTwo && quantityAsInt > TWO_FOR_AMOUNT_QUANTITY) {
+                double discountAmount = quantity * unitPrice - ((numberOfXs * TWO_FOR_AMOUNT_QUANTITY * unitPrice) + quantityAsInt % THREE_FOR_TWO_QUANTITY * unitPrice);
                 char description[MAX_NAME_LENGTH];
-                sprintf(description, "3 for 2");
+                sprintf(description, THREE_FOR_TWO_DESCRIPTION);
                 discount = discount_create(description, -discountAmount, &product);
             }
             if (offer->type == TenPercentDiscount) {
                 char description[MAX_NAME_LENGTH];
-                sprintf(description, "%.0f%% off", offer->argument);
-                discount = discount_create(description, -quantity * unitPrice * offer->argument / 100.0, &product);
+                sprintf(description, PERCENT_OFF_FORMAT, offer->argument);
+                discount = discount_create(description, -quantity * unitPrice * offer->argument / PERCENTAGE_DIVISOR, &product);
 
             }
-            if (offer->type == FiveForAmount && quantityAsInt >= 5) {
-                double discountTotal = unitPrice * quantity - (offer->argument * numberOfXs + quantityAsInt % 5 * unitPrice);
+            if (offer->type == FiveForAmount && quantityAsInt >= FIVE_FOR_AMOUNT_QUANTITY) {
+                double discountTotal = unitPrice * quantity - (offer->argument * numberOfXs + quantityAsInt % FIVE_FOR_AMOUNT_QUANTITY * unitPrice);
                 char description[MAX_NAME_LENGTH];
-                sprintf(description, "%d for %f", x, offer->argument);
+                sprintf(description, FOR_FORMAT, x, offer->argument);
                 discount = discount_create(description, -discountTotal, &product);
             }
             if (discount != NULL) {
diff --git a/common-lisp/source/shopping-cart.lisp b/common-lisp/source/shopping-cart.lisp
index 51631a2..ba7d1c0 100644
--- a/common-lisp/source/shopping-cart.lisp
+++ b/common-lisp/source/shopping-cart.lisp
@@ -2,6 +2,16 @@
 
 (in-package :supermarket-receipt)
 
+;;; Constants for magic numbers
+(defconstant +default-item-quantity+ 1.0)
+(defconstant +two-for-amount-quantity+ 2)
+(defconstant +three-for-two-quantity+ 3)
+(defconstant +five-for-amount-quantity+ 5)
+(defconstant +percentage-divisor+ 100.0)
+
+;;; Constants for discount description strings
+(defconstant +three-for-two-description+ "3 for 2")
+
 (defclass shopping-cart ()
         ((items :initform nil
                 :type list
@@ -11,7 +21,7 @@
                     :accessor shopping-cart-product-quantities)))
 
 (defmethod add-item ((a-cart shopping-cart) (an-item product))
-    (add-item-quantity a-cart an-item 1.0))
+    (add-item-quantity a-cart an-item +default-item-quantity+))
 
 (defmethod add-item-quantity ((a-cart shopping-cart) (an-item product) (a-quantity single-float))
     (push (make-instance 'product-quantity
@@ -35,39 +45,39 @@
                         (x 1)
                         (the-offer-type (offer-type offer-for-product)))
                     (if (eq the-offer-type 'three-for-two)
-                        (setf x 3)
+                        (setf x +three-for-two-quantity+)
                         (when (eq the-offer-type 'two-for-amount)
-                          (setf x 2)
-                          (when (>= floored-quantity 2)
+                          (setf x +two-for-amount-quantity+)
+                          (when (>= floored-quantity +two-for-amount-quantity+)
                             (let* ((total (+ (* (offer-argument offer-for-product) (floor (/ floored-quantity x)))
-                                             (* (mod floored-quantity 2) a-unit-price)))
+                                             (* (mod floored-quantity +two-for-amount-quantity+) a-unit-price)))
                                    (discount-n (- (* a-unit-price a-quantity) total)))
                               (setf a-discount (make-instance 'discount 
                                                               :product a-product
                                                               :description (format nil "2 for ~S" (offer-argument offer-for-product))
                                                               :amount (- discount-n)))))))
                     (when (eq the-offer-type 'five-for-amount)
-                      (setf x 5))
+                      (setf x +five-for-amount-quantity+))
                     (let ((number-of-x (floor (/ floored-quantity x))))
                       (when (and (eq the-offer-type 'three-for-two)
-                                 (> floored-quantity 2))
+                                 (> floored-quantity +two-for-amount-quantity+))
                         (let ((discount-amount (- (* a-quantity a-unit-price)
-                                                  (+ (* number-of-x 2 a-unit-price)
-                                                     (* (mod floored-quantity 3) a-unit-price)))))
+                                                  (+ (* number-of-x +two-for-amount-quantity+ a-unit-price)
+                                                     (* (mod floored-quantity +three-for-two-quantity+) a-unit-price)))))
                           (setf a-discount (make-instance 'discount
                                                           :product a-product
-                                                          :description "3 for 2"
+                                                          :description +three-for-two-description+
                                                           :amount (- discount-amount)))))
                       (when (eq the-offer-type 'ten-percent-discount)
                         (setf a-discount (make-instance 'discount
                                                         :product a-product
                                                         :description (format nil "~S % off" (offer-argument offer-for-product))
-                                                        :amount (/ (* (- a-quantity) a-unit-price (offer-argument offer-for-product)) 100.0))))
+                                                        :amount (/ (* (- a-quantity) a-unit-price (offer-argument offer-for-product)) +percentage-divisor+))))
                       (when (and (eq the-offer-type 'five-for-amount)
-                                 (>= floored-quantity 5))
+                                 (>= floored-quantity +five-for-amount-quantity+))
                         (let ((discount-total (- (* a-quantity a-unit-price)
                                                  (+ (* (offer-argument offer-for-product) number-of-x)
-                                                    (* (mod floored-quantity 5) a-unit-price)))))
+                                                    (* (mod floored-quantity +five-for-amount-quantity+) a-unit-price)))))
                           (setf a-discount (make-instance 'discount
                                                           :product a-product
                                                           :description (format nil "~S for ~S" x (offer-argument offer-for-product))
diff --git a/cpp/src/ShoppingCart.cpp b/cpp/src/ShoppingCart.cpp
index 3c3a523..faf4540 100644
--- a/cpp/src/ShoppingCart.cpp
+++ b/cpp/src/ShoppingCart.cpp
@@ -1,5 +1,20 @@
 #include "ShoppingCart.h"
 
+// Constants for magic numbers
+namespace {
+    constexpr double DEFAULT_ITEM_QUANTITY = 1.0;
+    constexpr int TWO_FOR_AMOUNT_QUANTITY = 2;
+    constexpr int THREE_FOR_TWO_QUANTITY = 3;
+    constexpr int FIVE_FOR_AMOUNT_QUANTITY = 5;
+    constexpr double PERCENTAGE_DIVISOR = 100.0;
+
+    // Constants for discount description strings
+    const std::string THREE_FOR_TWO_DESCRIPTION = "3 for 2";
+    const std::string TWO_FOR_PREFIX = "2 for ";
+    const std::string FOR_SEPARATOR = " for ";
+    const std::string PERCENT_OFF_SUFFIX = "% off";
+}
+
 void addItemQuantity(const Product& product, double quantity);
 
 std::vector<ProductQuantity> ShoppingCart::getItems() const {
@@ -11,7 +26,7 @@ std::map<Product, double> ShoppingCart::getProductQuantities() const {
 }
 
 void ShoppingCart::addItem(const Product& product) {
-    addItemQuantity(product, 1.0);
+    addItemQuantity(product, DEFAULT_ITEM_QUANTITY);
 }
 
 void ShoppingCart::addItemQuantity(const Product& product, double quantity) {
@@ -35,28 +50,28 @@ void ShoppingCart::handleOffers(Receipt& receipt, std::map<Product, Offer> offer
             int x = 1;
 
             if (offer.getOfferType() == SpecialOfferType::ThreeForTwo) {
-                x = 3;
+                x = THREE_FOR_TWO_QUANTITY;
             } else if (offer.getOfferType() == SpecialOfferType::TwoForAmount) {
-                x = 2;
-                if (quantityAsInt >= 2) {
-                    double total = offer.getArgument() * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
+                x = TWO_FOR_AMOUNT_QUANTITY;
+                if (quantityAsInt >= TWO_FOR_AMOUNT_QUANTITY) {
+                    double total = offer.getArgument() * (quantityAsInt / x) + quantityAsInt % TWO_FOR_AMOUNT_QUANTITY * unitPrice;
                     double discountN = unitPrice * quantity - total;
-                    discount = new Discount("2 for " + std::to_string(offer.getArgument()), -discountN, product);
+                    discount = new Discount(TWO_FOR_PREFIX + std::to_string(offer.getArgument()), -discountN, product);
                 }
             } if (offer.getOfferType() == SpecialOfferType::FiveForAmount) {
-                x = 5;
+                x = FIVE_FOR_AMOUNT_QUANTITY;
             }
             int numberOfXs = quantityAsInt / x;
-            if (offer.getOfferType() == SpecialOfferType::ThreeForTwo && quantityAsInt > 2) {
-                double discountAmount = quantity * unitPrice - ((numberOfXs * 2 * unitPrice) + quantityAsInt % 3 * unitPrice);
-                discount = new Discount("3 for 2", -discountAmount, product);
+            if (offer.getOfferType() == SpecialOfferType::ThreeForTwo && quantityAsInt > TWO_FOR_AMOUNT_QUANTITY) {
+                double discountAmount = quantity * unitPrice - ((numberOfXs * TWO_FOR_AMOUNT_QUANTITY * unitPrice) + quantityAsInt % THREE_FOR_TWO_QUANTITY * unitPrice);
+                discount = new Discount(THREE_FOR_TWO_DESCRIPTION, -discountAmount, product);
             }
             if (offer.getOfferType() == SpecialOfferType::TenPercentDiscount) {
-                discount = new Discount(std::to_string(offer.getArgument()) + "% off", -quantity * unitPrice * offer.getArgument() / 100.0, product);
+                discount = new Discount(std::to_string(offer.getArgument()) + PERCENT_OFF_SUFFIX, -quantity * unitPrice * offer.getArgument() / PERCENTAGE_DIVISOR, product);
             }
-            if (offer.getOfferType() == SpecialOfferType::FiveForAmount && quantityAsInt >= 5) {
-                double discountTotal = unitPrice * quantity - (offer.getArgument() * numberOfXs + quantityAsInt % 5 * unitPrice);
-                discount = new Discount(std::to_string(x) + " for " + std::to_string(offer.getArgument()), -discountTotal, product);
+            if (offer.getOfferType() == SpecialOfferType::FiveForAmount && quantityAsInt >= FIVE_FOR_AMOUNT_QUANTITY) {
+                double discountTotal = unitPrice * quantity - (offer.getArgument() * numberOfXs + quantityAsInt % FIVE_FOR_AMOUNT_QUANTITY * unitPrice);
+                discount = new Discount(std::to_string(x) + FOR_SEPARATOR + std::to_string(offer.getArgument()), -discountTotal, product);
             }
             if (discount != nullptr)
                 receipt.addDiscount(*discount);
diff --git a/csharp-ms/SupermarketReceipt/ShoppingCart.cs b/csharp-ms/SupermarketReceipt/ShoppingCart.cs
index 28abbe7..4965286 100644
--- a/csharp-ms/SupermarketReceipt/ShoppingCart.cs
+++ b/csharp-ms/SupermarketReceipt/ShoppingCart.cs
@@ -4,6 +4,19 @@ namespace SupermarketReceipt
 {
     public class ShoppingCart
     {
+        // Constants for magic numbers
+        private const double DefaultItemQuantity = 1.0;
+        private const int TwoForAmountQuantity = 2;
+        private const int ThreeForTwoQuantity = 3;
+        private const int FiveForAmountQuantity = 5;
+        private const double PercentageDivisor = 100.0;
+
+        // Constants for discount description strings
+        private const string ThreeForTwoDescription = "3 for 2";
+        private const string TwoForPrefix = "2 for ";
+        private const string ForSeparator = " for ";
+        private const string PercentOffSuffix = "% off";
+
         private readonly List<ProductQuantity> _items = new List<ProductQuantity>();
         private readonly Dictionary<Product, double> _productQuantities = new Dictionary<Product, double>();
 
@@ -15,7 +28,7 @@ public List<ProductQuantity> GetItems()
 
         public void AddItem(Product product)
         {
-            AddItemQuantity(product, 1.0);
+            AddItemQuantity(product, DefaultItemQuantity);
         }
 
 
@@ -47,32 +60,32 @@ public void HandleOffers(Receipt receipt, Dictionary<Product, Offer> offers, Sup
                     var x = 1;
                     if (offer.OfferType == SpecialOfferType.ThreeForTwo)
                     {
-                        x = 3;
+                        x = ThreeForTwoQuantity;
                     }
                     else if (offer.OfferType == SpecialOfferType.TwoForAmount)
                     {
-                        x = 2;
-                        if (quantityAsInt >= 2)
+                        x = TwoForAmountQuantity;
+                        if (quantityAsInt >= TwoForAmountQuantity)
                         {
-                            var total = offer.Argument * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
+                            var total = offer.Argument * (quantityAsInt / x) + quantityAsInt % TwoForAmountQuantity * unitPrice;
                             var discountN = unitPrice * quantity - total;
-                            discount = new Discount(p, "2 for " + offer.Argument, -discountN);
+                            discount = new Discount(p, TwoForPrefix + offer.Argument, -discountN);
                         }
                     }
 
-                    if (offer.OfferType == SpecialOfferType.FiveForAmount) x = 5;
+                    if (offer.OfferType == SpecialOfferType.FiveForAmount) x = FiveForAmountQuantity;
                     var numberOfXs = quantityAsInt / x;
-                    if (offer.OfferType == SpecialOfferType.ThreeForTwo && quantityAsInt > 2)
+                    if (offer.OfferType == SpecialOfferType.ThreeForTwo && quantityAsInt > TwoForAmountQuantity)
                     {
-                        var discountAmount = quantity * unitPrice - (numberOfXs * 2 * unitPrice + quantityAsInt % 3 * unitPrice);
-                        discount = new Discount(p, "3 for 2", -discountAmount);
+                        var discountAmount = quantity * unitPrice - (numberOfXs * TwoForAmountQuantity * unitPrice + quantityAsInt % ThreeForTwoQuantity * unitPrice);
+                        discount = new Discount(p, ThreeForTwoDescription, -discountAmount);
                     }
 
-                    if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + "% off", -quantity * unitPrice * offer.Argument / 100.0);
-                    if (offer.OfferType == SpecialOfferType.FiveForAmount && quantityAsInt >= 5)
+                    if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + PercentOffSuffix, -quantity * unitPrice * offer.Argument / PercentageDivisor);
+                    if (offer.OfferType == SpecialOfferType.FiveForAmount && quantityAsInt >= FiveForAmountQuantity)
                     {
-                        var discountTotal = unitPrice * quantity - (offer.Argument * numberOfXs + quantityAsInt % 5 * unitPrice);
-                        discount = new Discount(p, x + " for " + offer.Argument, -discountTotal);
+                        var discountTotal = unitPrice * quantity - (offer.Argument * numberOfXs + quantityAsInt % FiveForAmountQuantity * unitPrice);
+                        discount = new Discount(p, x + ForSeparator + offer.Argument, -discountTotal);
                     }
 
                     if (discount != null)
diff --git a/csharp/SupermarketReceipt/ShoppingCart.cs b/csharp/SupermarketReceipt/ShoppingCart.cs
index 72b6b4a..f2069e2 100644
--- a/csharp/SupermarketReceipt/ShoppingCart.cs
+++ b/csharp/SupermarketReceipt/ShoppingCart.cs
@@ -5,6 +5,19 @@ namespace SupermarketReceipt
 {
     public class ShoppingCart
     {
+        // Constants for magic numbers
+        private const double DefaultItemQuantity = 1.0;
+        private const int TwoForAmountQuantity = 2;
+        private const int ThreeForTwoQuantity = 3;
+        private const int FiveForAmountQuantity = 5;
+        private const double PercentageDivisor = 100.0;
+
+        // Constants for discount description strings
+        private const string ThreeForTwoDescription = "3 for 2";
+        private const string TwoForPrefix = "2 for ";
+        private const string ForSeparator = " for ";
+        private const string PercentOffSuffix = "% off";
+
         private readonly List<ProductQuantity> _items = new List<ProductQuantity>();
         private readonly Dictionary<Product, double> _productQuantities = new Dictionary<Product, double>();
         private static readonly CultureInfo Culture = CultureInfo.CreateSpecificCulture("en-GB");
@@ -17,7 +30,7 @@ public List<ProductQuantity> GetItems()
 
         public void AddItem(Product product)
         {
-            AddItemQuantity(product, 1.0);
+            AddItemQuantity(product, DefaultItemQuantity);
         }
 
 
@@ -49,32 +62,32 @@ public void HandleOffers(Receipt receipt, Dictionary<Product, Offer> offers, Sup
                     var x = 1;
                     if (offer.OfferType == SpecialOfferType.ThreeForTwo)
                     {
-                        x = 3;
+                        x = ThreeForTwoQuantity;
                     }
                     else if (offer.OfferType == SpecialOfferType.TwoForAmount)
                     {
-                        x = 2;
-                        if (quantityAsInt >= 2)
+                        x = TwoForAmountQuantity;
+                        if (quantityAsInt >= TwoForAmountQuantity)
                         {
-                            var total = offer.Argument * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
+                            var total = offer.Argument * (quantityAsInt / x) + quantityAsInt % TwoForAmountQuantity * unitPrice;
                             var discountN = unitPrice * quantity - total;
-                            discount = new Discount(p, "2 for " + PrintPrice(offer.Argument), -discountN);
+                            discount = new Discount(p, TwoForPrefix + PrintPrice(offer.Argument), -discountN);
                         }
                     }
 
-                    if (offer.OfferType == SpecialOfferType.FiveForAmount) x = 5;
+                    if (offer.OfferType == SpecialOfferType.FiveForAmount) x = FiveForAmountQuantity;
                     var numberOfXs = quantityAsInt / x;
-                    if (offer.OfferType == SpecialOfferType.ThreeForTwo && quantityAsInt > 2)
+                    if (offer.OfferType == SpecialOfferType.ThreeForTwo && quantityAsInt > TwoForAmountQuantity)
                     {
-                        var discountAmount = quantity * unitPrice - (numberOfXs * 2 * unitPrice + quantityAsInt % 3 * unitPrice);
-                        discount = new Discount(p, "3 for 2", -discountAmount);
+                        var discountAmount = quantity * unitPrice - (numberOfXs * TwoForAmountQuantity * unitPrice + quantityAsInt % ThreeForTwoQuantity * unitPrice);
+                        discount = new Discount(p, ThreeForTwoDescription, -discountAmount);
                     }
 
-                    if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + "% off", -quantity * unitPrice * offer.Argument / 100.0);
-                    if (offer.OfferType == SpecialOfferType.FiveForAmount && quantityAsInt >= 5)
+                    if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + PercentOffSuffix, -quantity * unitPrice * offer.Argument / PercentageDivisor);
+                    if (offer.OfferType == SpecialOfferType.FiveForAmount && quantityAsInt >= FiveForAmountQuantity)
                     {
-                        var discountTotal = unitPrice * quantity - (offer.Argument * numberOfXs + quantityAsInt % 5 * unitPrice);
-                        discount = new Discount(p, x + " for " + PrintPrice(offer.Argument), -discountTotal);
+                        var discountTotal = unitPrice * quantity - (offer.Argument * numberOfXs + quantityAsInt % FiveForAmountQuantity * unitPrice);
+                        discount = new Discount(p, x + ForSeparator + PrintPrice(offer.Argument), -discountTotal);
                     }
 
                     if (discount != null)
diff --git a/elixir/lib/supermarket/model/shopping_cart.ex b/elixir/lib/supermarket/model/shopping_cart.ex
index b0fc089..463b784 100644
--- a/elixir/lib/supermarket/model/shopping_cart.ex
+++ b/elixir/lib/supermarket/model/shopping_cart.ex
@@ -5,12 +5,22 @@ defmodule Supermarket.Model.ShoppingCart do
   alias Supermarket.Model.Receipt
   alias Supermarket.Model.SupermarketCatalog
 
+  # Constants for magic numbers
+  @default_item_quantity 1.0
+  @two_for_amount_quantity 2
+  @three_for_two_quantity 3
+  @five_for_amount_quantity 5
+  @percentage_divisor 100.0
+
+  # Constants for discount description strings
+  @three_for_two_description "3 for 2"
+
   defstruct [:items, :product_quantities]
 
   def new, do: %__MODULE__{items: [], product_quantities: %{}}
 
   def add_item(cart, product) do
-    add_item_quantity(cart, product, 1.0)
+    add_item_quantity(cart, product, @default_item_quantity)
   end
 
   def add_item_quantity(cart, product, quantity) do
@@ -41,48 +51,48 @@ defmodule Supermarket.Model.ShoppingCart do
         {discount, x} =
           cond do
             offer.offer_type == :three_for_two ->
-              {discount, 3}
+              {discount, @three_for_two_quantity}
 
             offer.offer_type == :two_for_amount ->
-              if quantity_as_int >= 2 do
-                x = 2
+              if quantity_as_int >= @two_for_amount_quantity do
+                x = @two_for_amount_quantity
                 int_division = div(quantity_as_int, x)
                 price_per_unit = offer.argument * int_division
-                the_total = Integer.mod(quantity_as_int, 2) * unit_price
+                the_total = Integer.mod(quantity_as_int, @two_for_amount_quantity) * unit_price
                 total = price_per_unit + the_total
                 discount_n = unit_price * quantity - total
-                {Discount.new(p, "2 for #{offer.argument}", -discount_n), 2}
+                {Discount.new(p, "2 for #{offer.argument}", -discount_n), @two_for_amount_quantity}
               else
                 {discount, x}
               end
 
             true ->
-              {discount, 2}
+              {discount, @two_for_amount_quantity}
           end
 
-        x = if offer.offer_type == :five_for_amount, do: 5, else: x
+        x = if offer.offer_type == :five_for_amount, do: @five_for_amount_quantity, else: x
         number_of_xs = div(quantity_as_int, x)
 
         discount =
           cond do
-            offer.offer_type == :three_for_two and quantity_as_int > 2 ->
+            offer.offer_type == :three_for_two and quantity_as_int > @two_for_amount_quantity ->
               discount_amount =
                 quantity * unit_price -
-                  (number_of_xs * 2 * unit_price + Integer.mod(quantity_as_int, 3) * unit_price)
+                  (number_of_xs * @two_for_amount_quantity * unit_price + Integer.mod(quantity_as_int, @three_for_two_quantity) * unit_price)
 
-              Discount.new(p, "3 for 2", -discount_amount)
+              Discount.new(p, @three_for_two_description, -discount_amount)
 
             offer.offer_type == :ten_percent_discount ->
               Discount.new(
                 p,
                 "#{offer.argument}% off",
-                -quantity * unit_price * offer.argument / 100.0
+                -quantity * unit_price * offer.argument / @percentage_divisor
               )
 
-            offer.offer_type == :five_for_amount and quantity_as_int >= 5 ->
+            offer.offer_type == :five_for_amount and quantity_as_int >= @five_for_amount_quantity ->
               discount_total =
                 unit_price * quantity -
-                  (offer.argument * number_of_xs + Integer.mod(quantity_as_int, 5) * unit_price)
+                  (offer.argument * number_of_xs + Integer.mod(quantity_as_int, @five_for_amount_quantity) * unit_price)
 
               Discount.new(p, "#{x} for #{offer.argument}", -discount_total)
 
diff --git a/go/supermarket/shopping_cart.go b/go/supermarket/shopping_cart.go
index 3079f92..9736ac2 100644
--- a/go/supermarket/shopping_cart.go
+++ b/go/supermarket/shopping_cart.go
@@ -5,6 +5,23 @@ import (
 	"math"
 )
 
+// Constants for magic numbers
+const (
+	defaultItemQuantity   = 1.0
+	twoForAmountQuantity  = 2
+	threeForTwoQuantity   = 3
+	fiveForAmountQuantity = 5
+	percentageDivisor     = 100.0
+)
+
+// Constants for discount description strings
+const (
+	threeForTwoDescription = "3 for 2"
+	twoForPrefix           = "2 for %.2f"
+	forSeparatorFormat     = "%d for %.2f"
+	percentOffSuffixFormat = "%.0f %% off"
+)
+
 type ProductQuantity struct {
 	product Product
 	quantity float64
@@ -23,7 +40,7 @@ func NewShoppingCart() *ShoppingCart {
 }
 
 func (c *ShoppingCart) addItem(product Product) {
-	c.addItemQuantity(product, 1)
+	c.addItemQuantity(product, defaultItemQuantity)
 }
 
 func (c *ShoppingCart) addItemQuantity(product Product, amount float64) {
@@ -45,31 +62,31 @@ func (c *ShoppingCart) handleOffers(receipt *Receipt, offers map[Product]Special
 			var discount *Discount = nil
 			var x = 1
 			if offer.offerType == ThreeForTwo {
-				x = 3
+				x = threeForTwoQuantity
 
 			} else if offer.offerType == TwoForAmount {
-				x = 2
-				if quantityAsInt >= 2 {
-					var total = offer.argument * float64(quantityAsInt / x) + float64(quantityAsInt % 2) * unitPrice
+				x = twoForAmountQuantity
+				if quantityAsInt >= twoForAmountQuantity {
+					var total = offer.argument * float64(quantityAsInt / x) + float64(quantityAsInt % twoForAmountQuantity) * unitPrice
 					var discountN = unitPrice * quantity - total;
-					discount = &Discount{product: p, description: fmt.Sprintf("2 for %.2f", offer.argument), discountAmount: -discountN}
+					discount = &Discount{product: p, description: fmt.Sprintf(twoForPrefix, offer.argument), discountAmount: -discountN}
 				}
 
 			}
 			if offer.offerType == FiveForAmount {
-				x = 5
+				x = fiveForAmountQuantity
 			}
 			var numberOfXs int = quantityAsInt / x;
-			if offer.offerType == ThreeForTwo && quantityAsInt > 2 {
-				var discountAmount = quantity * unitPrice - (float64(numberOfXs * 2) * unitPrice + float64(quantityAsInt % 3) * unitPrice)
-				discount = &Discount{product: p, description: "3 for 2", discountAmount: -discountAmount}
+			if offer.offerType == ThreeForTwo && quantityAsInt > twoForAmountQuantity {
+				var discountAmount = quantity * unitPrice - (float64(numberOfXs * twoForAmountQuantity) * unitPrice + float64(quantityAsInt % threeForTwoQuantity) * unitPrice)
+				discount = &Discount{product: p, description: threeForTwoDescription, discountAmount: -discountAmount}
 			}
 			if offer.offerType == TenPercentDiscount {
-				discount = &Discount{product: p, description: fmt.Sprintf("%.0f %% off", offer.argument), discountAmount: -quantity * unitPrice * offer.argument / 100.0}
+				discount = &Discount{product: p, description: fmt.Sprintf(percentOffSuffixFormat, offer.argument), discountAmount: -quantity * unitPrice * offer.argument / percentageDivisor}
 			}
-			if offer.offerType == FiveForAmount && quantityAsInt >= 5 {
-				var discountTotal = unitPrice * quantity - (offer.argument * float64(numberOfXs) + float64(quantityAsInt % 5) * unitPrice)
-				discount = &Discount{product: p, description: fmt.Sprintf("%d for %.2f", x, offer.argument), discountAmount: -discountTotal}
+			if offer.offerType == FiveForAmount && quantityAsInt >= fiveForAmountQuantity {
+				var discountTotal = unitPrice * quantity - (offer.argument * float64(numberOfXs) + float64(quantityAsInt % fiveForAmountQuantity) * unitPrice)
+				discount = &Discount{product: p, description: fmt.Sprintf(forSeparatorFormat, x, offer.argument), discountAmount: -discountTotal}
 			}
 			if discount != nil {
 				receipt.addDiscount(*discount)
diff --git a/java/src/main/java/dojo/supermarket/model/ShoppingCart.java b/java/src/main/java/dojo/supermarket/model/ShoppingCart.java
index 9293086..844e725 100644
--- a/java/src/main/java/dojo/supermarket/model/ShoppingCart.java
+++ b/java/src/main/java/dojo/supermarket/model/ShoppingCart.java
@@ -8,6 +8,19 @@
 
 public class ShoppingCart {
 
+    // Constants for magic numbers
+    private static final double DEFAULT_ITEM_QUANTITY = 1.0;
+    private static final int TWO_FOR_AMOUNT_QUANTITY = 2;
+    private static final int THREE_FOR_TWO_QUANTITY = 3;
+    private static final int FIVE_FOR_AMOUNT_QUANTITY = 5;
+    private static final double PERCENTAGE_DIVISOR = 100.0;
+
+    // Constants for discount description strings
+    private static final String THREE_FOR_TWO_DESCRIPTION = "3 for 2";
+    private static final String TWO_FOR_PREFIX = "2 for ";
+    private static final String FOR_SEPARATOR = " for ";
+    private static final String PERCENT_OFF_SUFFIX = "% off";
+
     private final List<ProductQuantity> items = new ArrayList<>();
     private final Map<Product, Double> productQuantities = new HashMap<>();
 
@@ -16,7 +29,7 @@ List<ProductQuantity> getItems() {
     }
 
     void addItem(Product product) {
-        addItemQuantity(product, 1.0);
+        addItemQuantity(product, DEFAULT_ITEM_QUANTITY);
     }
 
     Map<Product, Double> productQuantities() {
@@ -42,30 +55,30 @@ void handleOffers(Receipt receipt, Map<Product, Offer> offers, SupermarketCatalo
                 Discount discount = null;
                 int x = 1;
                 if (offer.offerType == SpecialOfferType.THREE_FOR_TWO) {
-                    x = 3;
+                    x = THREE_FOR_TWO_QUANTITY;
 
                 } else if (offer.offerType == SpecialOfferType.TWO_FOR_AMOUNT) {
-                    x = 2;
-                    if (quantityAsInt >= 2) {
-                        double total = offer.argument * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
+                    x = TWO_FOR_AMOUNT_QUANTITY;
+                    if (quantityAsInt >= TWO_FOR_AMOUNT_QUANTITY) {
+                        double total = offer.argument * (quantityAsInt / x) + quantityAsInt % TWO_FOR_AMOUNT_QUANTITY * unitPrice;
                         double discountN = unitPrice * quantity - total;
-                        discount = new Discount(p, "2 for " + offer.argument, -discountN);
+                        discount = new Discount(p, TWO_FOR_PREFIX + offer.argument, -discountN);
                     }
 
                 } if (offer.offerType == SpecialOfferType.FIVE_FOR_AMOUNT) {
-                    x = 5;
+                    x = FIVE_FOR_AMOUNT_QUANTITY;
                 }
                 int numberOfXs = quantityAsInt / x;
-                if (offer.offerType == SpecialOfferType.THREE_FOR_TWO && quantityAsInt > 2) {
-                    double discountAmount = quantity * unitPrice - ((numberOfXs * 2 * unitPrice) + quantityAsInt % 3 * unitPrice);
-                    discount = new Discount(p, "3 for 2", -discountAmount);
+                if (offer.offerType == SpecialOfferType.THREE_FOR_TWO && quantityAsInt > TWO_FOR_AMOUNT_QUANTITY) {
+                    double discountAmount = quantity * unitPrice - ((numberOfXs * TWO_FOR_AMOUNT_QUANTITY * unitPrice) + quantityAsInt % THREE_FOR_TWO_QUANTITY * unitPrice);
+                    discount = new Discount(p, THREE_FOR_TWO_DESCRIPTION, -discountAmount);
                 }
                 if (offer.offerType == SpecialOfferType.TEN_PERCENT_DISCOUNT) {
-                    discount = new Discount(p, offer.argument + "% off", -quantity * unitPrice * offer.argument / 100.0);
+                    discount = new Discount(p, offer.argument + PERCENT_OFF_SUFFIX, -quantity * unitPrice * offer.argument / PERCENTAGE_DIVISOR);
                 }
-                if (offer.offerType == SpecialOfferType.FIVE_FOR_AMOUNT && quantityAsInt >= 5) {
-                    double discountTotal = unitPrice * quantity - (offer.argument * numberOfXs + quantityAsInt % 5 * unitPrice);
-                    discount = new Discount(p, x + " for " + offer.argument, -discountTotal);
+                if (offer.offerType == SpecialOfferType.FIVE_FOR_AMOUNT && quantityAsInt >= FIVE_FOR_AMOUNT_QUANTITY) {
+                    double discountTotal = unitPrice * quantity - (offer.argument * numberOfXs + quantityAsInt % FIVE_FOR_AMOUNT_QUANTITY * unitPrice);
+                    discount = new Discount(p, x + FOR_SEPARATOR + offer.argument, -discountTotal);
                 }
                 if (discount != null)
                     receipt.addDiscount(discount);
diff --git a/kotlin/src/main/kotlin/supermarket/model/ShoppingCart.kt b/kotlin/src/main/kotlin/supermarket/model/ShoppingCart.kt
index 83e7f30..2b43f4f 100644
--- a/kotlin/src/main/kotlin/supermarket/model/ShoppingCart.kt
+++ b/kotlin/src/main/kotlin/supermarket/model/ShoppingCart.kt
@@ -3,6 +3,19 @@ package supermarket.model
 import java.util.ArrayList
 import java.util.HashMap
 
+// Constants for magic numbers
+private const val DEFAULT_ITEM_QUANTITY = 1.0
+private const val TWO_FOR_AMOUNT_QUANTITY = 2
+private const val THREE_FOR_TWO_QUANTITY = 3
+private const val FIVE_FOR_AMOUNT_QUANTITY = 5
+private const val PERCENTAGE_DIVISOR = 100.0
+
+// Constants for discount description strings
+private const val THREE_FOR_TWO_DESCRIPTION = "3 for 2"
+private const val TWO_FOR_PREFIX = "2 for "
+private const val FOR_SEPARATOR = " for "
+private const val PERCENT_OFF_SUFFIX = "% off"
+
 class ShoppingCart {
 
     private val items = ArrayList<ProductQuantity>()
@@ -14,7 +27,7 @@ class ShoppingCart {
     }
 
     internal fun addItem(product: Product) {
-        this.addItemQuantity(product, 1.0)
+        this.addItemQuantity(product, DEFAULT_ITEM_QUANTITY)
     }
 
     internal fun productQuantities(): Map<Product, Double> {
@@ -41,34 +54,34 @@ class ShoppingCart {
                 var discount: Discount? = null
                 var x = 1
                 if (offer.offerType === SpecialOfferType.ThreeForTwo) {
-                    x = 3
+                    x = THREE_FOR_TWO_QUANTITY
 
                 } else if (offer.offerType === SpecialOfferType.TwoForAmount) {
-                    x = 2
-                    if (quantityAsInt >= 2) {
-                        val total = offer.argument * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice
+                    x = TWO_FOR_AMOUNT_QUANTITY
+                    if (quantityAsInt >= TWO_FOR_AMOUNT_QUANTITY) {
+                        val total = offer.argument * (quantityAsInt / x) + quantityAsInt % TWO_FOR_AMOUNT_QUANTITY * unitPrice
                         val discountN = unitPrice * quantity - total
-                        discount = Discount(p, "2 for " + offer.argument, discountN)
+                        discount = Discount(p, TWO_FOR_PREFIX + offer.argument, discountN)
                     }
 
                 }
                 if (offer.offerType === SpecialOfferType.FiveForAmount) {
-                    x = 5
+                    x = FIVE_FOR_AMOUNT_QUANTITY
                 }
                 val numberOfXs = quantityAsInt / x
-                if (offer.offerType === SpecialOfferType.ThreeForTwo && quantityAsInt > 2) {
+                if (offer.offerType === SpecialOfferType.ThreeForTwo && quantityAsInt > TWO_FOR_AMOUNT_QUANTITY) {
                     val discountAmount =
-                        quantity * unitPrice - (numberOfXs.toDouble() * 2.0 * unitPrice + quantityAsInt % 3 * unitPrice)
-                    discount = Discount(p, "3 for 2", discountAmount)
+                        quantity * unitPrice - (numberOfXs.toDouble() * TWO_FOR_AMOUNT_QUANTITY.toDouble() * unitPrice + quantityAsInt % THREE_FOR_TWO_QUANTITY * unitPrice)
+                    discount = Discount(p, THREE_FOR_TWO_DESCRIPTION, discountAmount)
                 }
                 if (offer.offerType === SpecialOfferType.TenPercentDiscount) {
                     discount =
-                        Discount(p, offer.argument.toString() + "% off", quantity * unitPrice * offer.argument / 100.0)
+                        Discount(p, offer.argument.toString() + PERCENT_OFF_SUFFIX, quantity * unitPrice * offer.argument / PERCENTAGE_DIVISOR)
                 }
-                if (offer.offerType === SpecialOfferType.FiveForAmount && quantityAsInt >= 5) {
+                if (offer.offerType === SpecialOfferType.FiveForAmount && quantityAsInt >= FIVE_FOR_AMOUNT_QUANTITY) {
                     val discountTotal =
-                        unitPrice * quantity - (offer.argument * numberOfXs + quantityAsInt % 5 * unitPrice)
-                    discount = Discount(p, x.toString() + " for " + offer.argument, discountTotal)
+                        unitPrice * quantity - (offer.argument * numberOfXs + quantityAsInt % FIVE_FOR_AMOUNT_QUANTITY * unitPrice)
+                    discount = Discount(p, x.toString() + FOR_SEPARATOR + offer.argument, discountTotal)
                 }
                 if (discount != null)
                     receipt.addDiscount(discount)
diff --git a/php/src/Model/ShoppingCart.php b/php/src/Model/ShoppingCart.php
index d2f6c78..38159b2 100644
--- a/php/src/Model/ShoppingCart.php
+++ b/php/src/Model/ShoppingCart.php
@@ -8,6 +8,19 @@
 
 class ShoppingCart
 {
+    // Constants for magic numbers
+    private const DEFAULT_ITEM_QUANTITY = 1.0;
+    private const TWO_FOR_AMOUNT_QUANTITY = 2;
+    private const THREE_FOR_TWO_QUANTITY = 3;
+    private const FIVE_FOR_AMOUNT_QUANTITY = 5;
+    private const PERCENTAGE_DIVISOR = 100.0;
+
+    // Constants for discount description strings
+    private const THREE_FOR_TWO_DESCRIPTION = '3 for 2';
+    private const TWO_FOR_PREFIX = '2 for ';
+    private const FOR_SEPARATOR = ' for ';
+    private const PERCENT_OFF_SUFFIX = '% off';
+
     /**
      * @var ProductQuantity[]
      */
@@ -25,7 +38,7 @@ public function __construct()
 
     public function addItem(Product $product): void
     {
-        $this->addItemQuantity($product, 1.0);
+        $this->addItemQuantity($product, self::DEFAULT_ITEM_QUANTITY);
     }
 
     /**
@@ -65,35 +78,35 @@ public function handleOffers(Receipt $receipt, Map $offers, SupermarketCatalog $
                 $discount = null;
                 $x = 1;
                 if ($offer->getOfferType()->equals(SpecialOfferType::THREE_FOR_TWO())) {
-                    $x = 3;
+                    $x = self::THREE_FOR_TWO_QUANTITY;
                 } elseif ($offer->getOfferType()->equals(SpecialOfferType::TWO_FOR_AMOUNT())) {
-                    $x = 2;
-                    if ($quantityAsInt >= 2) {
-                        $total = $offer->getArgument() * intdiv($quantityAsInt, $x) + $quantityAsInt % 2 * $unitPrice;
+                    $x = self::TWO_FOR_AMOUNT_QUANTITY;
+                    if ($quantityAsInt >= self::TWO_FOR_AMOUNT_QUANTITY) {
+                        $total = $offer->getArgument() * intdiv($quantityAsInt, $x) + $quantityAsInt % self::TWO_FOR_AMOUNT_QUANTITY * $unitPrice;
                         $discountN = $unitPrice * $quantity - $total;
-                        $discount = new Discount($p, "2 for {$offer->getArgument()}", -1 * $discountN);
+                        $discount = new Discount($p, self::TWO_FOR_PREFIX . "{$offer->getArgument()}", -1 * $discountN);
                     }
                 }
 
                 if ($offer->getOfferType()->equals(SpecialOfferType::FIVE_FOR_AMOUNT())) {
-                    $x = 5;
+                    $x = self::FIVE_FOR_AMOUNT_QUANTITY;
                 }
                 $numberOfXs = intdiv($quantityAsInt, $x);
-                if ($offer->getOfferType()->equals(SpecialOfferType::THREE_FOR_TWO()) && $quantityAsInt > 2) {
-                    $discountAmount = $quantity * $unitPrice - ($numberOfXs * 2 * $unitPrice + $quantityAsInt % 3 * $unitPrice);
-                    $discount = new Discount($p, '3 for 2', -$discountAmount);
+                if ($offer->getOfferType()->equals(SpecialOfferType::THREE_FOR_TWO()) && $quantityAsInt > self::TWO_FOR_AMOUNT_QUANTITY) {
+                    $discountAmount = $quantity * $unitPrice - ($numberOfXs * self::TWO_FOR_AMOUNT_QUANTITY * $unitPrice + $quantityAsInt % self::THREE_FOR_TWO_QUANTITY * $unitPrice);
+                    $discount = new Discount($p, self::THREE_FOR_TWO_DESCRIPTION, -$discountAmount);
                 }
 
                 if ($offer->getOfferType()->equals(SpecialOfferType::TEN_PERCENT_DISCOUNT())) {
                     $discount = new Discount(
                         $p,
-                        "{$offer->getArgument()}% off",
-                        -$quantity * $unitPrice * $offer->getArgument() / 100.0
+                        "{$offer->getArgument()}" . self::PERCENT_OFF_SUFFIX,
+                        -$quantity * $unitPrice * $offer->getArgument() / self::PERCENTAGE_DIVISOR
                     );
                 }
-                if ($offer->getOfferType()->equals(SpecialOfferType::FIVE_FOR_AMOUNT()) && $quantityAsInt >= 5) {
-                    $discountTotal = $unitPrice * $quantity - ($offer->getArgument() * $numberOfXs + $quantityAsInt % 5 * $unitPrice);
-                    $discount = new Discount($p, "${x} for {$offer->getArgument()}", -$discountTotal);
+                if ($offer->getOfferType()->equals(SpecialOfferType::FIVE_FOR_AMOUNT()) && $quantityAsInt >= self::FIVE_FOR_AMOUNT_QUANTITY) {
+                    $discountTotal = $unitPrice * $quantity - ($offer->getArgument() * $numberOfXs + $quantityAsInt % self::FIVE_FOR_AMOUNT_QUANTITY * $unitPrice);
+                    $discount = new Discount($p, "${x}" . self::FOR_SEPARATOR . "{$offer->getArgument()}", -$discountTotal);
                 }
 
                 if ($discount !== null) {
diff --git a/python/receipt_printer.py b/python/receipt_printer.py
index 7550fe9..7e58ab4 100644
--- a/python/receipt_printer.py
+++ b/python/receipt_printer.py
@@ -1,8 +1,14 @@
 from model_objects import ProductUnit
 
+# Constants for magic numbers and strings
+DEFAULT_COLUMNS = 40
+SINGLE_ITEM_QUANTITY = 1
+TOTAL_LABEL = "Total: "
+
+
 class ReceiptPrinter:
 
-    def __init__(self, columns=40):
+    def __init__(self, columns=DEFAULT_COLUMNS):
         self.columns = columns
   
     def print_receipt(self, receipt):
@@ -23,7 +29,7 @@ def print_receipt_item(self, item):
         total_price_printed = self.print_price(item.total_price)
         name = item.product.name
         line = self.format_line_with_whitespace(name, total_price_printed)
-        if item.quantity != 1:
+        if item.quantity != SINGLE_ITEM_QUANTITY:
             line += f"  {self.print_price(item.price)} * {self.print_quantity(item)}\n"
         return line
 
@@ -51,6 +57,6 @@ def print_discount(self, discount):
         return self.format_line_with_whitespace(name, value)
 
     def present_total(self, receipt):
-        name = "Total: "
+        name = TOTAL_LABEL
         value = self.print_price(receipt.total_price())
         return self.format_line_with_whitespace(name, value)
diff --git a/python/shopping_cart.py b/python/shopping_cart.py
index 4e36cc5..d7f3058 100644
--- a/python/shopping_cart.py
+++ b/python/shopping_cart.py
@@ -2,6 +2,19 @@
 
 from model_objects import ProductQuantity, SpecialOfferType, Discount
 
+# Constants for magic numbers
+DEFAULT_ITEM_QUANTITY = 1.0
+TWO_FOR_AMOUNT_QUANTITY = 2
+THREE_FOR_TWO_QUANTITY = 3
+FIVE_FOR_AMOUNT_QUANTITY = 5
+PERCENTAGE_DIVISOR = 100.0
+
+# Constants for discount description strings
+THREE_FOR_TWO_DESCRIPTION = "3 for 2"
+TWO_FOR_PREFIX = "2 for "
+FOR_SEPARATOR = " for "
+PERCENT_OFF_SUFFIX = "% off"
+
 
 class ShoppingCart:
 
@@ -14,7 +27,7 @@ def items(self):
         return self._items
 
     def add_item(self, product):
-        self.add_item_quantity(product, 1.0)
+        self.add_item_quantity(product, DEFAULT_ITEM_QUANTITY)
 
     @property
     def product_quantities(self):
@@ -37,32 +50,32 @@ def handle_offers(self, receipt, offers, catalog):
                 discount = None
                 x = 1
                 if offer.offer_type == SpecialOfferType.THREE_FOR_TWO:
-                    x = 3
+                    x = THREE_FOR_TWO_QUANTITY
 
                 elif offer.offer_type == SpecialOfferType.TWO_FOR_AMOUNT:
-                    x = 2
-                    if quantity_as_int >= 2:
-                        total = offer.argument * (quantity_as_int / x) + quantity_as_int % 2 * unit_price
+                    x = TWO_FOR_AMOUNT_QUANTITY
+                    if quantity_as_int >= TWO_FOR_AMOUNT_QUANTITY:
+                        total = offer.argument * (quantity_as_int / x) + quantity_as_int % TWO_FOR_AMOUNT_QUANTITY * unit_price
                         discount_n = unit_price * quantity - total
-                        discount = Discount(p, "2 for " + str(offer.argument), -discount_n)
+                        discount = Discount(p, TWO_FOR_PREFIX + str(offer.argument), -discount_n)
 
                 if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT:
-                    x = 5
+                    x = FIVE_FOR_AMOUNT_QUANTITY
 
                 number_of_x = math.floor(quantity_as_int / x)
-                if offer.offer_type == SpecialOfferType.THREE_FOR_TWO and quantity_as_int > 2:
+                if offer.offer_type == SpecialOfferType.THREE_FOR_TWO and quantity_as_int > TWO_FOR_AMOUNT_QUANTITY:
                     discount_amount = quantity * unit_price - (
-                                (number_of_x * 2 * unit_price) + quantity_as_int % 3 * unit_price)
-                    discount = Discount(p, "3 for 2", -discount_amount)
+                                (number_of_x * TWO_FOR_AMOUNT_QUANTITY * unit_price) + quantity_as_int % THREE_FOR_TWO_QUANTITY * unit_price)
+                    discount = Discount(p, THREE_FOR_TWO_DESCRIPTION, -discount_amount)
 
                 if offer.offer_type == SpecialOfferType.TEN_PERCENT_DISCOUNT:
-                    discount = Discount(p, str(offer.argument) + "% off",
-                                        -quantity * unit_price * offer.argument / 100.0)
+                    discount = Discount(p, str(offer.argument) + PERCENT_OFF_SUFFIX,
+                                        -quantity * unit_price * offer.argument / PERCENTAGE_DIVISOR)
 
-                if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT and quantity_as_int >= 5:
+                if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT and quantity_as_int >= FIVE_FOR_AMOUNT_QUANTITY:
                     discount_total = unit_price * quantity - (
-                                offer.argument * number_of_x + quantity_as_int % 5 * unit_price)
-                    discount = Discount(p, str(x) + " for " + str(offer.argument), -discount_total)
+                                offer.argument * number_of_x + quantity_as_int % FIVE_FOR_AMOUNT_QUANTITY * unit_price)
+                    discount = Discount(p, str(x) + FOR_SEPARATOR + str(offer.argument), -discount_total)
 
                 if discount:
                     receipt.add_discount(discount)
diff --git a/python_pytest/src/shopping_cart.py b/python_pytest/src/shopping_cart.py
index 4e36cc5..d7f3058 100644
--- a/python_pytest/src/shopping_cart.py
+++ b/python_pytest/src/shopping_cart.py
@@ -2,6 +2,19 @@
 
 from model_objects import ProductQuantity, SpecialOfferType, Discount
 
+# Constants for magic numbers
+DEFAULT_ITEM_QUANTITY = 1.0
+TWO_FOR_AMOUNT_QUANTITY = 2
+THREE_FOR_TWO_QUANTITY = 3
+FIVE_FOR_AMOUNT_QUANTITY = 5
+PERCENTAGE_DIVISOR = 100.0
+
+# Constants for discount description strings
+THREE_FOR_TWO_DESCRIPTION = "3 for 2"
+TWO_FOR_PREFIX = "2 for "
+FOR_SEPARATOR = " for "
+PERCENT_OFF_SUFFIX = "% off"
+
 
 class ShoppingCart:
 
@@ -14,7 +27,7 @@ def items(self):
         return self._items
 
     def add_item(self, product):
-        self.add_item_quantity(product, 1.0)
+        self.add_item_quantity(product, DEFAULT_ITEM_QUANTITY)
 
     @property
     def product_quantities(self):
@@ -37,32 +50,32 @@ def handle_offers(self, receipt, offers, catalog):
                 discount = None
                 x = 1
                 if offer.offer_type == SpecialOfferType.THREE_FOR_TWO:
-                    x = 3
+                    x = THREE_FOR_TWO_QUANTITY
 
                 elif offer.offer_type == SpecialOfferType.TWO_FOR_AMOUNT:
-                    x = 2
-                    if quantity_as_int >= 2:
-                        total = offer.argument * (quantity_as_int / x) + quantity_as_int % 2 * unit_price
+                    x = TWO_FOR_AMOUNT_QUANTITY
+                    if quantity_as_int >= TWO_FOR_AMOUNT_QUANTITY:
+                        total = offer.argument * (quantity_as_int / x) + quantity_as_int % TWO_FOR_AMOUNT_QUANTITY * unit_price
                         discount_n = unit_price * quantity - total
-                        discount = Discount(p, "2 for " + str(offer.argument), -discount_n)
+                        discount = Discount(p, TWO_FOR_PREFIX + str(offer.argument), -discount_n)
 
                 if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT:
-                    x = 5
+                    x = FIVE_FOR_AMOUNT_QUANTITY
 
                 number_of_x = math.floor(quantity_as_int / x)
-                if offer.offer_type == SpecialOfferType.THREE_FOR_TWO and quantity_as_int > 2:
+                if offer.offer_type == SpecialOfferType.THREE_FOR_TWO and quantity_as_int > TWO_FOR_AMOUNT_QUANTITY:
                     discount_amount = quantity * unit_price - (
-                                (number_of_x * 2 * unit_price) + quantity_as_int % 3 * unit_price)
-                    discount = Discount(p, "3 for 2", -discount_amount)
+                                (number_of_x * TWO_FOR_AMOUNT_QUANTITY * unit_price) + quantity_as_int % THREE_FOR_TWO_QUANTITY * unit_price)
+                    discount = Discount(p, THREE_FOR_TWO_DESCRIPTION, -discount_amount)
 
                 if offer.offer_type == SpecialOfferType.TEN_PERCENT_DISCOUNT:
-                    discount = Discount(p, str(offer.argument) + "% off",
-                                        -quantity * unit_price * offer.argument / 100.0)
+                    discount = Discount(p, str(offer.argument) + PERCENT_OFF_SUFFIX,
+                                        -quantity * unit_price * offer.argument / PERCENTAGE_DIVISOR)
 
-                if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT and quantity_as_int >= 5:
+                if offer.offer_type == SpecialOfferType.FIVE_FOR_AMOUNT and quantity_as_int >= FIVE_FOR_AMOUNT_QUANTITY:
                     discount_total = unit_price * quantity - (
-                                offer.argument * number_of_x + quantity_as_int % 5 * unit_price)
-                    discount = Discount(p, str(x) + " for " + str(offer.argument), -discount_total)
+                                offer.argument * number_of_x + quantity_as_int % FIVE_FOR_AMOUNT_QUANTITY * unit_price)
+                    discount = Discount(p, str(x) + FOR_SEPARATOR + str(offer.argument), -discount_total)
 
                 if discount:
                     receipt.add_discount(discount)
diff --git a/ruby/lib/models/shopping_cart.rb b/ruby/lib/models/shopping_cart.rb
index 6eea42e..138169f 100644
--- a/ruby/lib/models/shopping_cart.rb
+++ b/ruby/lib/models/shopping_cart.rb
@@ -1,3 +1,16 @@
+# Constants for magic numbers
+DEFAULT_ITEM_QUANTITY = 1.0
+TWO_FOR_AMOUNT_QUANTITY = 2
+THREE_FOR_TWO_QUANTITY = 3
+FIVE_FOR_AMOUNT_QUANTITY = 5
+PERCENTAGE_DIVISOR = 100.0
+
+# Constants for discount description strings
+THREE_FOR_TWO_DESCRIPTION = "3 for 2"
+TWO_FOR_PREFIX = "2 for "
+FOR_SEPARATOR = " for "
+PERCENT_OFF_SUFFIX = "% off"
+
 class ShoppingCart
 
   def initialize
@@ -10,7 +23,7 @@ def items
   end
 
   def add_item(product)
-    add_item_quantity(product, 1.0)
+    add_item_quantity(product, DEFAULT_ITEM_QUANTITY)
     nil
   end
 
@@ -37,31 +50,31 @@ def handle_offers(receipt, offers, catalog)
         discount = nil
         x = 1
         if offer.offer_type == SpecialOfferType::THREE_FOR_TWO
-          x = 3
+          x = THREE_FOR_TWO_QUANTITY
 
         elsif offer.offer_type == SpecialOfferType::TWO_FOR_AMOUNT
-          x = 2
-          if quantity_as_int >= 2
-            total = offer.argument * (quantity_as_int / x) + quantity_as_int % 2 * unit_price
+          x = TWO_FOR_AMOUNT_QUANTITY
+          if quantity_as_int >= TWO_FOR_AMOUNT_QUANTITY
+            total = offer.argument * (quantity_as_int / x) + quantity_as_int % TWO_FOR_AMOUNT_QUANTITY * unit_price
             discount_n = unit_price * quantity - total
-            discount = Discount.new(p, "2 for " + offer.argument.to_s, discount_n)
+            discount = Discount.new(p, TWO_FOR_PREFIX + offer.argument.to_s, discount_n)
           end
 
         end
         if offer.offer_type == SpecialOfferType:: FIVE_FOR_AMOUNT
-          x = 5
+          x = FIVE_FOR_AMOUNT_QUANTITY
         end
         number_of_x = quantity_as_int / x
-        if offer.offer_type == SpecialOfferType::THREE_FOR_TWO && quantity_as_int > 2
-          discount_amount = quantity * unit_price - ((number_of_x * 2 * unit_price) + quantity_as_int % 3 * unit_price)
-          discount = Discount.new(p, "3 for 2", discount_amount)
+        if offer.offer_type == SpecialOfferType::THREE_FOR_TWO && quantity_as_int > TWO_FOR_AMOUNT_QUANTITY
+          discount_amount = quantity * unit_price - ((number_of_x * TWO_FOR_AMOUNT_QUANTITY * unit_price) + quantity_as_int % THREE_FOR_TWO_QUANTITY * unit_price)
+          discount = Discount.new(p, THREE_FOR_TWO_DESCRIPTION, discount_amount)
         end
         if offer.offer_type == SpecialOfferType::TEN_PERCENT_DISCOUNT
-          discount = Discount.new(p, offer.argument.to_s + "% off", quantity * unit_price * offer.argument / 100.0)
+          discount = Discount.new(p, offer.argument.to_s + PERCENT_OFF_SUFFIX, quantity * unit_price * offer.argument / PERCENTAGE_DIVISOR)
         end
-        if offer.offer_type == SpecialOfferType::FIVE_FOR_AMOUNT && quantity_as_int >= 5
-          discount_total = unit_price * quantity - (offer.argument * number_of_x + quantity_as_int % 5 * unit_price)
-          discount = Discount.new(p, x.to_s + " for " + offer.argument.to_s, discount_total)
+        if offer.offer_type == SpecialOfferType::FIVE_FOR_AMOUNT && quantity_as_int >= FIVE_FOR_AMOUNT_QUANTITY
+          discount_total = unit_price * quantity - (offer.argument * number_of_x + quantity_as_int % FIVE_FOR_AMOUNT_QUANTITY * unit_price)
+          discount = Discount.new(p, x.to_s + FOR_SEPARATOR + offer.argument.to_s, discount_total)
         end
 
         receipt.add_discount(discount) if discount
diff --git a/swift/SupermarketReceipt/ShoppingCart.swift b/swift/SupermarketReceipt/ShoppingCart.swift
index d34c8bc..6edbc53 100644
--- a/swift/SupermarketReceipt/ShoppingCart.swift
+++ b/swift/SupermarketReceipt/ShoppingCart.swift
@@ -1,10 +1,23 @@
+// Constants for magic numbers
+private let defaultItemQuantity = 1.0
+private let twoForAmountQuantity = 2
+private let threeForTwoQuantity = 3
+private let fiveForAmountQuantity = 5
+private let percentageDivisor = 100.0
+
+// Constants for discount description strings
+private let threeForTwoDescription = "3 for 2"
+private let twoForPrefix = "2 for "
+private let forSeparator = " for "
+private let percentOffSuffix = "% off"
+
 public class ShoppingCart {
 
     public var items = [ProductQuantity]()
     public var productQuantities = [Product: Double]()
 
     func addItem(product: Product) {
-        self.addItemQuantity(product: product, quantity: 1.0)
+        self.addItemQuantity(product: product, quantity: defaultItemQuantity)
     }
 
     public func addItemQuantity(product: Product , quantity: Double) {
@@ -26,42 +39,42 @@ public class ShoppingCart {
                 var discount: Discount? = nil
                 var x = 1
                 if offer?.offerType == SpecialOfferType.ThreeForTwo {
-                    x = 3
+                    x = threeForTwoQuantity
 
                 } else if offer?.offerType == SpecialOfferType.TwoForAmount {
-                    x = 2
-                    if (quantityAsInt >= 2) {
+                    x = twoForAmountQuantity
+                    if (quantityAsInt >= twoForAmountQuantity) {
                         
                         var intDivision = quantityAsInt / x
                         
                         var pricePerUnit = (offer!.argument * Double(intDivision))
                         
-                        var theTotal = Double(quantityAsInt % 2) * unitPrice
+                        var theTotal = Double(quantityAsInt % twoForAmountQuantity) * unitPrice
                         
                         var total = pricePerUnit + theTotal
                         var discountN = unitPrice * quantity! - total
-                        discount =  Discount(description:  "2 for \(offer!.argument)", discountAmount: discountN, product: p)
+                        discount =  Discount(description:  twoForPrefix + "\(offer!.argument)", discountAmount: discountN, product: p)
                     }
 
                 } else if offer?.offerType == SpecialOfferType.FiveForAmount {
-                    x = 5
+                    x = fiveForAmountQuantity
                 }
                 var numberOfXs = quantityAsInt / x
-                if offer?.offerType == SpecialOfferType.ThreeForTwo && quantityAsInt > 2 {
-                    var left = Double(numberOfXs * 2) * unitPrice
-                    var right = Double(quantityAsInt % 3) * unitPrice
+                if offer?.offerType == SpecialOfferType.ThreeForTwo && quantityAsInt > twoForAmountQuantity {
+                    var left = Double(numberOfXs * twoForAmountQuantity) * unitPrice
+                    var right = Double(quantityAsInt % threeForTwoQuantity) * unitPrice
                     var lastPart = left + right
                     var discountAmount = ((quantity ?? 1) * unitPrice) - lastPart
-                    discount =  Discount(description: "3 for 2", discountAmount: discountAmount, product: p)
+                    discount =  Discount(description: threeForTwoDescription, discountAmount: discountAmount, product: p)
                 }
                 if offer?.offerType == SpecialOfferType.TenPercentDiscount {
-                    discount =  Discount(description: "\(offer!.argument)% off", discountAmount: (quantity ?? 1) * unitPrice * (offer?.argument ?? 1) / 100.0, product: p)
+                    discount =  Discount(description: "\(offer!.argument)" + percentOffSuffix, discountAmount: (quantity ?? 1) * unitPrice * (offer?.argument ?? 1) / percentageDivisor, product: p)
                 }
-                if offer?.offerType == SpecialOfferType.FiveForAmount && quantityAsInt >= 5 {
+                if offer?.offerType == SpecialOfferType.FiveForAmount && quantityAsInt >= fiveForAmountQuantity {
                     var left = (unitPrice * (quantity ?? 1))
-                    var right = ((offer?.argument ?? 1) * Double(numberOfXs)) + (Double(quantityAsInt % 5) * unitPrice)
+                    var right = ((offer?.argument ?? 1) * Double(numberOfXs)) + (Double(quantityAsInt % fiveForAmountQuantity) * unitPrice)
                     var discountTotal = left - right
-                    discount =  Discount(description: "\(x) for \(offer!.argument)", discountAmount: discountTotal,  product: p)
+                    discount =  Discount(description: "\(x)" + forSeparator + "\(offer!.argument)", discountAmount: discountTotal,  product: p)
                 }
                 if discount != nil {
                     receipt.addDiscount(discount: discount!)
diff --git a/typescript/src/model/ShoppingCart.ts b/typescript/src/model/ShoppingCart.ts
index ac090cc..9a979bd 100644
--- a/typescript/src/model/ShoppingCart.ts
+++ b/typescript/src/model/ShoppingCart.ts
@@ -7,6 +7,19 @@ import {Receipt} from "./Receipt"
 import {Offer} from "./Offer"
 import {SpecialOfferType} from "./SpecialOfferType"
 
+// Constants for magic numbers
+const DEFAULT_ITEM_QUANTITY = 1.0;
+const TWO_FOR_AMOUNT_QUANTITY = 2;
+const THREE_FOR_TWO_QUANTITY = 3;
+const FIVE_FOR_AMOUNT_QUANTITY = 5;
+const PERCENTAGE_DIVISOR = 100.0;
+
+// Constants for discount description strings
+const THREE_FOR_TWO_DESCRIPTION = "3 for 2";
+const TWO_FOR_PREFIX = "2 for ";
+const FOR_SEPARATOR = " for ";
+const PERCENT_OFF_SUFFIX = "% off";
+
 type ProductQuantities = { [productName: string]: ProductQuantity }
 export type OffersByProduct = {[productName: string]: Offer};
 
@@ -21,7 +34,7 @@ export class ShoppingCart {
     }
 
     addItem(product: Product): void {
-        this.addItemQuantity(product, 1.0);
+        this.addItemQuantity(product, DEFAULT_ITEM_QUANTITY);
     }
 
     productQuantities(): ProductQuantities {
@@ -57,30 +70,30 @@ export class ShoppingCart {
                 let discount : Discount|null = null;
                 let x = 1;
                 if (offer.offerType == SpecialOfferType.ThreeForTwo) {
-                    x = 3;
+                    x = THREE_FOR_TWO_QUANTITY;
 
                 } else if (offer.offerType == SpecialOfferType.TwoForAmount) {
-                    x = 2;
-                    if (quantityAsInt >= 2) {
-                        const total = offer.argument * Math.floor(quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
+                    x = TWO_FOR_AMOUNT_QUANTITY;
+                    if (quantityAsInt >= TWO_FOR_AMOUNT_QUANTITY) {
+                        const total = offer.argument * Math.floor(quantityAsInt / x) + quantityAsInt % TWO_FOR_AMOUNT_QUANTITY * unitPrice;
                         const discountN = unitPrice * quantity - total;
-                        discount = new Discount(product, "2 for " + offer.argument, discountN);
+                        discount = new Discount(product, TWO_FOR_PREFIX + offer.argument, discountN);
                     }
 
                 } if (offer.offerType == SpecialOfferType.FiveForAmount) {
-                    x = 5;
+                    x = FIVE_FOR_AMOUNT_QUANTITY;
                 }
                 const numberOfXs = Math.floor(quantityAsInt / x);
-                if (offer.offerType == SpecialOfferType.ThreeForTwo && quantityAsInt > 2) {
-                    const discountAmount = quantity * unitPrice - ((numberOfXs * 2 * unitPrice) + quantityAsInt % 3 * unitPrice);
-                    discount = new Discount(product, "3 for 2", discountAmount);
+                if (offer.offerType == SpecialOfferType.ThreeForTwo && quantityAsInt > TWO_FOR_AMOUNT_QUANTITY) {
+                    const discountAmount = quantity * unitPrice - ((numberOfXs * TWO_FOR_AMOUNT_QUANTITY * unitPrice) + quantityAsInt % THREE_FOR_TWO_QUANTITY * unitPrice);
+                    discount = new Discount(product, THREE_FOR_TWO_DESCRIPTION, discountAmount);
                 }
                 if (offer.offerType == SpecialOfferType.TenPercentDiscount) {
-                    discount = new Discount(product, offer.argument + "% off", quantity * unitPrice * offer.argument / 100.0);
+                    discount = new Discount(product, offer.argument + PERCENT_OFF_SUFFIX, quantity * unitPrice * offer.argument / PERCENTAGE_DIVISOR);
                 }
-                if (offer.offerType == SpecialOfferType.FiveForAmount && quantityAsInt >= 5) {
-                    const discountTotal = unitPrice * quantity - (offer.argument * numberOfXs + quantityAsInt % 5 * unitPrice);
-                    discount = new Discount(product, x + " for " + offer.argument, discountTotal);
+                if (offer.offerType == SpecialOfferType.FiveForAmount && quantityAsInt >= FIVE_FOR_AMOUNT_QUANTITY) {
+                    const discountTotal = unitPrice * quantity - (offer.argument * numberOfXs + quantityAsInt % FIVE_FOR_AMOUNT_QUANTITY * unitPrice);
+                    discount = new Discount(product, x + FOR_SEPARATOR + offer.argument, discountTotal);
                 }
                 if (discount != null)
                     receipt.addDiscount(discount);