calculator.py

def add(a, b):
    return a+b


def multiply(a, b):
    return a * b


def divide(a, b):
    if b != 0:
        return a / b
    else:
        print("You can't divide by 0")


def subtract(a, b):
    return a - b


def main():
    # in reality I'd NEVER use 'while True' for something like this but this is
    # a simple "get back into programming" project
    while True:
        # display menu
        print("Menu:\n")
        print("\tAdd")
        print("\tSubtract")
        print("\tMultiply")
        print("\tDivide")
        print("\tQuit")

        # define variables
        choice = input("What is your choice: ")
        results = 0

        # process choice
        if choice.lower() == "quit" or choice.lower() == "q":
            break
        elif choice == "add" or choice == "a":
            results = add(int(input("First Number: ")),
            int(input("Second Number: ")))
        elif choice == "subtract" or choice == "s":
            results = subtract(int(input("First Number: ")),
            int(input("Second Number: ")))
        elif choice == "multiply" or choice == "m":
            results = multiply(int(input("First Number: ")),
            int(input("Second Number: ")))
        elif choice == "divide" or choice == "d":
            results = divide(int(input("First Number: ")),
            int(input("Second Number: ")))
        print("Results are: " + str(results))

    print("Goodbye")


main()