diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..d99f2f3
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,6 @@
+{
+    "[python]": {
+        "editor.defaultFormatter": "ms-python.black-formatter"
+    },
+    "python.formatting.provider": "none"
+}
\ No newline at end of file
diff --git a/challenges/01-calc.py b/challenges/01-calc.py
index 87f5190..158cf83 100644
--- a/challenges/01-calc.py
+++ b/challenges/01-calc.py
@@ -2,3 +2,80 @@
 # input() always returns a string value. If you ever want someone
 # to enter a number you have to use the `int()` function to convert
 # what they typed in to a string.
+
+# is_running = True
+
+# while is_running:
+#     operation = input("Which calculation would you like to do? (add, sub, mult, div) \n")
+#     num1 = float(input("what is number 1? \n"))
+#     num2 = float(input("what is number 2? \n"))
+
+#     if operation == 'add':
+#         result = num1 + num2
+#     elif operation == 'sub':
+#         result = num1 - num2
+#     elif operation == 'mult':
+#         result = num1 * num2
+#     elif operation == 'div':
+#         if num2 != 0:
+#             result = num1 / num2
+#         else:
+#             print("IMPOSSIBLE to divide by ZERO")
+#     else:
+#         print("That wasn't an option... (add, sub, mult, div)")
+#     print(f"Your result is {result}.")
+
+#     done = input("Do another calculation? (yes, no)\n")
+#     if done.lower() == "no":
+#         break
+
+is_running = True
+
+while is_running:
+    # display math choices and ask user to choose one
+    prompt = "> "
+    print("Hello, user")
+    print("What kind of math would you like to do?")
+    print("add, sub, mul, div?")
+    math_choice = input(prompt)
+    print (f"math choice: {math_choice}")
+
+    #ask the user to input two numbers, one by one
+    print("Enter the first number to use.")
+    number_one = input(prompt)
+    print("Now the second number.")
+    number_two = input(prompt)
+
+    print(number_one, number_two)
+
+    try:
+        # convert input to integers
+        number_one = int(number_one)
+        number_two = int(number_two)
+
+        # dictionary switch
+        switch = {
+            "add": number_one + number_two,
+            "sub": number_one - number_two, 
+            "mul": number_one * number_two,
+            "div": number_one / number_two
+        }
+
+        if math_choice in switch:
+            print(f'result: {switch[math_choice]}')
+        else:
+        #default for the switch case
+            print(f"I lied, {math_choice} isn't a math I know about!")
+
+    except ValueError as e:
+        print("That wasn't a real number!")
+
+    # ask the user if they would like to exit
+    print("Would you like to continue doing math? (y/n)\n")
+    should_quit = input(prompt)
+    if should_quit == "n":
+        is_running = False
+
+    
+    
+
diff --git a/challenges/02-reverse.py b/challenges/02-reverse.py
index 8cf2677..bc56f1a 100644
--- a/challenges/02-reverse.py
+++ b/challenges/02-reverse.py
@@ -6,3 +6,13 @@
 # several ways to reverse a string, and it's a good read!
 #
 # http://www.techbeamers.com/essential-python-tips-tricks-programmers/?utm_source=mybridge&utm_medium=blog&utm_campaign=read_more#tip1
+
+def reverse_str(str):
+    reversed_str = ""
+    i = len(str) - 1
+    while i >= 0:
+        reversed_str += str[i]
+        i -= 1
+    return reversed_str
+
+print(reverse_str("abcdef"))
\ No newline at end of file
diff --git a/challenges/03-bank.py b/challenges/03-bank.py
index 554cb1d..4277f29 100644
--- a/challenges/03-bank.py
+++ b/challenges/03-bank.py
@@ -1,3 +1,62 @@
-print("Welcome to Chase bank.")
-print("Have a nice day!")
+balance = 4000
 
+def banking():
+    print("Welcome to Chase bank.")
+
+    global balance
+
+    transaction = input("What would you like to do? (deposit, withdraw, balance)\n")
+
+    if transaction == 'deposit':
+        deposit_amount = float(input("How much would you like to deposit?\n"))
+        balance += deposit_amount
+        return f"Your new balance is {balance}."
+    elif transaction == 'withdraw':
+        withdraw_amount = float(input("How much would you like to withdraw?\n"))
+        balance -= withdraw_amount
+        return f"Your new balance is {balance}."
+    elif transaction == 'balance':
+        return f"Your current balance is {balance}."
+
+    print("Have a nice day!")
+
+# print(banking())
+
+def deposit(amount):
+    global balance
+    balance += amount
+    return balance
+
+def withdraw(amount):
+    global balance
+    if amount <= balance: #check if sufficient balance exists
+        balance -= amount
+    else:
+        print("Insufficient balance.")
+    return balance
+
+def check_balance():
+    global balance
+    return balance
+
+while True:
+    print(f"Your current balance is {balance}.")
+    transaction = input("What would you like to do? (deposit, withdraw, check_balance)\n")
+
+    if transaction == "deposit":
+        amount = int(input("How much would you like to deposit?\n"))
+        balance = deposit(amount)
+        print(f"Your current balance is {balance}")
+    elif transaction == "withdraw":
+        amount = int(input("How much would you like to withdraw?\n"))
+        balance = withdraw(amount)
+        print(f"Your current balance is {balance}")
+    elif transaction == "check_balance":
+        print(f"Your current balance is {balance}")
+    else:
+        print("Not a valid input. Select deposit, withdraw, check_balance.\n")
+
+    done = input("Are you done? (yes, no)\n")
+    if done.lower() == "yes":
+        print("Thank you!")
+        break
\ No newline at end of file
diff --git a/challenges/04-alphabetical.py b/challenges/04-alphabetical.py
index 5051ec4..3602758 100644
--- a/challenges/04-alphabetical.py
+++ b/challenges/04-alphabetical.py
@@ -1,3 +1,28 @@
 # You'll need to use a couple of built in functions to alphabetize a string. 
 # Try to avoid looking up the exact answer and look at built in functions for
 # lists and strings instead.
+
+def alphabetize(str):
+    # sorted_str = sorted(str)
+    
+    # stringified = ''.join(sorted_str)
+
+    # return stringified
+
+    return ''.join(sorted(str))
+
+print(alphabetize("supercalifragilisticexpialidocious"))
+
+# convert to list approach
+string = "antidisestablishmentarianism"
+string_list = list(string)
+string_list.sort()
+string = "".join(string_list)
+print(string)
+
+# python slice syntax
+my_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+# [slice start (default 0): slice end (default end of list): step (default 1)]
+my_list_copy = my_list[::] # make a copy with defaults
+print(my_list[::-1])
+print("racecar"[::-1])
\ No newline at end of file