Flask Calculator API

A lightweight Flask REST API for performing basic mathematical operations — addition, subtraction, multiplication, division, and square.
Built with simplicity and learning in mind, this project helps you understand how to create and test RESTful APIs using Flask.

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🚀 Features

• ➕ Add two numbers
• ➖ Subtract two numbers
• ✖️ Multiply two numbers
• ➗ Divide two numbers (with zero-check)
• 🔲 Square a single number
• ✅ Includes basic error handling for invalid or missing inputs

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🧱 Tech Stack

• Python 3.x
• Flask (for building REST APIs)
• JSON (for input/output data format)

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⚙️ Setup Instructions

1. Clone the repository

git clone https://github.com/your-username/flask-math-api.git
cd flask-math-api

2. Install Flask

pip install flask

3. Run the application

python app.py

Once the server starts, the API will be available at:

http://127.0.0.1:5000/

📡 API Endpoints

Method	Endpoint	Description	Required Fields
POST	/add	Add two numbers	num1, num2
POST	/subtract	Subtract two numbers	num1, num2
POST	/multiply	Multiply two numbers	num1, num2
POST	/divide	Divide two numbers	num1, num2
POST	/square	Find the square of a number	num
GET	/	Welcome route showing available endpoints	—

🧪 Example API Requests

➕ POST /add

Request Body (JSON):

{
  "num1": 10,
  "num2": 5
}

Response:

{
  "operation": "addition",
  "result": 15.0
}

➗ POST /divide (Example with Error) Request Body (JSON):

{
  "num1": 10,
  "num2": 0
}

Response:

{
  "error": "Division by zero is not allowed."
}

🧰 Testing the API with Postman

You can easily test this API using Postman:

1. Open Postman and click on New → HTTP Request.

2. Set the method to POST.

3. Enter the desired endpoint, for example: http://127.0.0.1:5000/add

4. Go to the Body tab → select raw → choose JSON from the dropdown.

5. Enter your JSON data, for example:

{
  "num1": 8,
  "num2": 4
}

Click Send — you'll receive a JSON response like:

{
  "operation": "addition",
  "result": 12.0
}

Repeat the same for /subtract, /multiply, /divide, or /square by changing the endpoint and body accordingly.

⚠️ Error Handling The API gracefully handles:

• Missing or invalid fields

• Non-numeric input

• Division by zero

• Invalid JSON format

• Example Error Response:

{
  "error": "Invalid input. Please provide valid JSON with 'num1' and 'num2'."
}