How to Create a Calculator Using Python 2.7.x

Hello guys, I am back. Today we will create a simple Calculator using Python 2.7.x version. This calculator perform basic mathematical operation such as add, minus, multiply and divide two number entered by user.
from __future__ import division

import os

import time
# This function adds two numbers 

def add(x, y):

   return x + y
# This function subtracts two numbers 

def subtract(x, y):

   return x – y
# This function multiplies two numbers

def multiply(x, y):

   return x * y
# This function divides two numbers

def divide(x, y):

   return x / y

while True:

    print(“Select operation.”)

    print(“1.Add”)

    print(“2.Subtract”)

    print(“3.Multiply”)

    print(“4.Divide”)
# Take input from the user

    try:

        choice = int(raw_input(“Enter choice(1/2/3/4):”))

    except:

        print “Invalid Value, Please Enter Right Option”

        time.sleep(5)

        os.system(‘cls’)

    else:

        try:

            num1 = int(raw_input(“Enter first number: “))

            num2 = int(raw_input(“Enter second number: “))

        except:

            print “Invalid Value”

            time.sleep(5)

            os.system(‘cls’)

        

        else:

            if choice == 1:

                print num1,’+’,num2,’=’, add(num1,num2)

                time.sleep(5)

                os.system(‘cls’)

            elif choice == 2:

                print num1,”-“,num2,”=”, subtract(num1,num2)

                time.sleep(5)

                os.system(‘cls’)

            elif choice == 3:

                print num1,”*”,num2,”=”, multiply(num1,num2)

                time.sleep(5)

                os.system(‘cls’)

            elif choice == 4:

                try:

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

                    time.sleep(5)

                    os.system(‘cls’)

                except ArithmeticError:

                    print “Arithmetic Error, Please Enter Right Value”

                    time.sleep(3)

                    os.system(‘cls’)

            else:

                 print “Invalid input”

                 time.sleep(5)

                 os.system(‘cls’)