calculator.py

def add(a, b):
    answer = a + b
    print(str(a) + " + ", str(b), " = " + str(answer) + "\n")

def sub(a, b):
    answer = a - b
    print(str(a) + " - ", str(b), " = " + str(answer) + "\n")

def multiply(a, b):
    answer = a * b
    print(str(a) + " x ", str(b), " = " + str(answer) + "\n")

def divide(a, b):
    answer = a / b
    print(str(a) + " / ", str(b), " = " + str(answer) + "\n")


while True:
    print("A, addition")
    print("B, subtraction")
    print("C, multiplication")
    print("D, division")
    print("E, exit")

    choice = input("Enter your choice: ")
    if choice == "a" or choice == "A":
        print("Addition")
        a = int(input("Enter your first number: "))
        b = int(input("Enter your second number: "))
        add(a, b)
    elif choice == "b" or choice == "B":
        print('Substraction')
        a = int(input("Enter your first number: "))
        b = int(input("Enter your second number: "))
        sub(a, b)
    elif choice == "c" or choice == "C":
        print('Multiplication')
        a = int(input("Enter your first number: "))
        b = int(input("Enter your second number: "))
        multiply(a, b)
    elif choice == "d" or choice == "D":
        print('Division')
        a = int(input("Enter your first number: "))
        b = int(input("Enter your second number:"))
        multiply(a, b)
    elif choice == "e" or choice == "E":
        print('Program ended')
        quit()