### Simple Calculator Project in Python with Source Code

A calculator is one of the most basic applications that one can build when learning a programming language. In this blog post, we will create a simple calculator using Python that can handle basic arithmetic operations: addition, subtraction, multiplication, and division.

# Requirements

A good understanding of Python basics, such as functions and taking user input.

# Steps to Create the Calculator

Setup the Basic Structure: Start by setting up a loop that continues to run until the user decides to exit.

Take User Input: Prompt the user to input two numbers and the operation they wish to perform.

Perform the Calculation: Based on the user's choice, perform the arithmetic operation. Display the Result: Show the result to the user.

Exit Option: Give the user an option to continue with another calculation or exit.

# Source 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):
if y == 0:
return "Undefined (division by zero)"
return x / y

while True:
print("Options:")
print("Enter 'subtract' for subtraction")
print("Enter 'multiply' for multiplication")
print("Enter 'divide' for division")
print("Enter 'quit' to end the program")
user_input = input(": ")

if user_input == "quit":
break
if user_input in ("add", "subtract", "multiply", "divide"):
x = float(input("Enter first number: "))
y = float(input("Enter second number: "))

elif user_input == "subtract":
print(subtract(x, y))
elif user_input == "multiply":
print(multiply(x, y))
elif user_input == "divide":
print(divide(x, y))
else:
print("Invalid Input")``````
``````
``````

Output:

``````Options:
Enter 'subtract' for subtraction
Enter 'multiply' for multiplication
Enter 'divide' for division
Enter 'quit' to end the program
Enter first number: 10
Enter second number: 20
30.0
Options:
Enter 'subtract' for subtraction
Enter 'multiply' for multiplication
Enter 'divide' for division
Enter 'quit' to end the program
: substract
Invalid Input
Options:
Enter 'subtract' for subtraction
Enter 'multiply' for multiplication
Enter 'divide' for division
Enter 'quit' to end the program
: subtract
Enter first number: 20
Enter second number: 12
8.0
Options:
Enter 'subtract' for subtraction
Enter 'multiply' for multiplication
Enter 'divide' for division
Enter 'quit' to end the program
: multiply
Enter first number: 10
Enter second number: 12
120.0
Options:
Enter 'subtract' for subtraction
Enter 'multiply' for multiplication
Enter 'divide' for division
Enter 'quit' to end the program
: divide
Enter first number: 10
Enter second number: 2
5.0
Options: