diff --git a/src/main/java/tdd/setup/Calculator.java b/src/main/java/tdd/setup/Calculator.java
index 171f6d6..4d92964 100644
--- a/src/main/java/tdd/setup/Calculator.java
+++ b/src/main/java/tdd/setup/Calculator.java
@@ -3,10 +3,15 @@
 // behaviour inspired by https://www.online-calculator.com/
 public class Calculator {
 
-    private String screen = "0";
+    private String screen = "";
 
     private double latestValue;
 
+    private double firstValue;
+
+    private double secondValue;
+    private double thirdValue;
+
     private String latestOperation = "";
 
     public String readScreen() {
@@ -17,11 +22,19 @@ public void pressDigitKey(int digit) {
 
         if(latestOperation.isEmpty()) {
             screen = screen + digit;
-        } else {
+            firstValue = Double.parseDouble(screen);
+
+        }
+        if(!screen.contains(".")) {
             latestValue = Double.parseDouble(screen);
             screen = Integer.toString(digit);
+
+        }
+            else {
+                screen = screen + digit;
+                latestValue = Double.parseDouble(screen);
+            }
         }
-    }
 
     public void pressClearKey() {
         screen = "0";
@@ -42,8 +55,8 @@ public void pressNegative() {
     }
 
     public void pressEquals() {
-        var result = switch(latestOperation) {
-            case "+" -> latestValue + Double.parseDouble(screen);
+        var result = switch(latestOperation){
+            case "+" -> firstValue + Double.parseDouble(screen);
             case "-" -> latestValue - Double.parseDouble(screen);
             case "x" -> latestValue * Double.parseDouble(screen);
             case "/" -> latestValue / Double.parseDouble(screen);
diff --git a/src/test/java/tdd/setup/CalculatorTest.java b/src/test/java/tdd/setup/CalculatorTest.java
index 3bf16e9..b6bf4eb 100644
--- a/src/test/java/tdd/setup/CalculatorTest.java
+++ b/src/test/java/tdd/setup/CalculatorTest.java
@@ -17,3 +17,39 @@ void calculatorCanDoTwoPlusTwo() {
         assertEquals("4", calc.readScreen());
     }
 }
+class CalculatorTest2 {
+    @Test
+    @DisplayName("should display result after subtracting two positive numbers")
+    void calculatorCanDoThreeMinusTwo() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(3);
+        calc.pressOperationKey("-");
+        calc.pressDigitKey(2);
+        calc.pressEquals();
+        assertEquals("1", calc.readScreen());
+    }
+}
+class CalculatorTest3 {
+    @Test
+    @DisplayName("should display result after pressDigitKey")
+    void calculatorCanMulti() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(2);
+        assertEquals("2", calc.readScreen());
+    }
+}
+class CalculatorTest4 {
+    @Test
+    @DisplayName("should display result after adding two positive point numbers")
+    void calculatorCanDoTwoPlusTwo() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(2);
+        calc.pressOperationKey("+");
+        calc.pressDigitKey(3);
+        calc.pressDotKey();
+        calc.pressDigitKey(4);
+        calc.pressEquals();
+        assertEquals("5.4", calc.readScreen());
+    }
+}
+