Python Program to Make a Simple Calculator

Levels of difficulty: / perform operation:
Source Code
# Program make a simple calculator that can add, subtract, multiply and divide using functions

# 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.")

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':
   print(num1,"/",num2,"=", divide(num1,num2))
   print("Invalid input")

In this program, we ask the user to choose the desired operation. Options 1,2,3 and 4 are valid. Two numbers are taken and an if…elif…else branching is used to execute a particular section. User-defined functions add(), subtract(), multiply() and divide() evaluate respective operations.