calculator.py

# A simple calculator that can add, subtract, multiply and divide

# define functions
def add(x, y):
   """This function adds two numbers"""

   return x + y

def subtract(x, y):
   """This function subtracts two numbers"""

   return x - y

def multiply(x, y):
   """This function multiplies two numbers"""

   return x * y

def divide(x, y):
   """This function divides two numbers"""

   return x / y

# take input from the user
print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")

choice = input("Enter choice(1/2/3/4):")

num1 = int(input("Enter first number: "))
num2 = int(input("Enter second number: "))

if choice == 1:
   print(num1,"+",num2,"=", add(num1,num2))

elif choice == 2:
   print(num1,"-",num2,"=", subtract(num1,num2))

elif choice == 3:
   print(num1,"*",num2,"=", multiply(num1,num2))

elif choice == 4:
  if num2 == 0:
    print(num1,"/",num2,"=", "Undifined")
  else:
    print(num1,"/",num2,"=", divide(num1,num2))

else:
   print("Invalid input")