Python Program to Make a Simple Calculator

In this example you will learn to create a simple calculator that can add, subtract, multiply or divide depending upon the input from the user.

To understand this example, you should have the knowledge of following Python programming topics:

Source Code: Simple Caculator by Making Functions

''' Program make a simple calculator that can add, subtract, multiply and divide using functions '''

# 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

print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")

# Take input from the user 
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))
else:
   print("Invalid input")

Output

Select operation.
1.Add
2.Subtract
3.Multiply
4.Divide
Enter choice(1/2/3/4): 3
Enter first number: 15
Enter second number: 14
15 * 14 = 210

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.