How to make a calculator in python?

Python Code: 

def add(x, y):

    return x + y

def subtract(x, y):

    return x - y

def multiply(x, y):

    return x * y

def divide(x, y):

    return x / y

print("Select operation.")

print("1. Add")

print("2. Subtract")

print("3. Multiply")

print("4. Divide")

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

num1 = float(input("Enter first number: "))

num2 = float(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':

    print(num1, "/", num2, "=", divide(num1,num2))

else:

    print("Invalid Input")