# Introduction

In this tutorial, we will learn how to build a simple calculator using Python. This is a great project for beginners to get hands-on experience with basic Python concepts such as functions, loops, and user input. By the end of this tutorial, you’ll have a fully functional calculator that can perform addition, subtraction, multiplication, and division.

## Prerequisites

Before we start, make sure you have Python installed on your computer. You can download it from the official Python website: python.org.

## Step 1: Setting Up the Project

First, let’s create a new Python file called `calculator.py`

. Open your favorite text editor or IDE and create the file.

## Step 2: Defining Functions for Operations

We will define functions for each of the basic arithmetic operations: addition, subtraction, multiplication, and division. Here’s the code:

```
# Function to add two numbers
def add(x, y):
return x + y
# Function to subtract two numbers
def subtract(x, y):
return x - y
# Function to multiply two numbers
def multiply(x, y):
return x * y
# Function to divide two numbers
def divide(x, y):
if y == 0:
return "Error! Division by zero."
return x / y
```

## Step 3: Creating the User Interface

Next, we’ll create a simple user interface that allows the user to choose an operation and input two numbers. Here’s how we can do it:

```
def calculator():
print("Select operation:")
print("1. Add")
print("2. Subtract")
print("3. Multiply")
print("4. Divide")
choice = input("Enter choice (1/2/3/4): ")
if choice in ('1', '2', '3', '4'):
num1 = float(input("Enter first number: "))
num2 = float(input("Enter second number: "))
if choice == '1':
print(f"{num1} + {num2} = {add(num1, num2)}")
elif choice == '2':
print(f"{num1} - {num2} = {subtract(num1, num2)}")
elif choice == '3':
print(f"{num1} * {num2} = {multiply(num1, num2)}")
elif choice == '4':
print(f"{num1} / {num2} = {divide(num1, num2)}")
else:
print("Invalid input")
if __name__ == "__main__":
while True:
calculator()
next_calculation = input("Do you want to perform another calculation? (yes/no): ")
if next_calculation.lower() != 'yes':
break
```

## Step 4: Running the Calculator

To run the calculator, simply execute the `calculator.py`

file. You can do this by opening a terminal or command prompt, navigating to the directory where the file is located, and running the following command:

`python calculator.py`

## Explanation

**Functions for Operations**: We defined functions for each arithmetic operation to keep our code organized and reusable.**User Interface**: The`calculator`

function provides a text-based menu for the user to select an operation and input numbers.**Input Handling**: We use the`input()`

function to get user input and convert it to float for arithmetic operations.**Control Flow**: We use if-elif statements to determine which operation to perform based on the user’s choice.**Loop**: We wrap the`calculator()`

call in a`while`

loop to allow the user to perform multiple calculations without restarting the program.

## Conclusion

Congratulations! You have successfully built a simple calculator using Python. This project covered fundamental concepts such as functions, loops, and user input handling. Feel free to expand this project by adding more operations or improving the user interface.

For more Python tutorials and projects, stay tuned to our blog. Happy coding!

This tutorial is designed to be clear and easy to follow, with explanations and code snippets to guide the reader through the process of building a simple calculator in Python.