app.py

from flask import Flask, render_template, request

app = Flask(__name__)

# Home Page
@app.route('/')
def home():
    return render_template('home.html')


# Prime Checker
@app.route('/prime', methods=['GET', 'POST'])
def prime():
    result = None

    if request.method == 'POST':
        num = int(request.form['number'])

        if num < 2:
            result = f"{num} is NOT a Prime Number"
        else:
            for i in range(2, int(num**0.5) + 1):
                if num % i == 0:
                    result = f"{num} is NOT a Prime Number"
                    break
            else:
                result = f"{num} is a Prime Number"

    return render_template('prime.html', result=result)


# Even Odd
@app.route('/evenodd', methods=['GET', 'POST'])
def evenodd():
    result = None

    if request.method == 'POST':
        num = int(request.form['number'])
        result = f"{num} is Even" if num % 2 == 0 else f"{num} is Odd"

    return render_template('evenodd.html', result=result)


# Calculator
@app.route('/calculator', methods=['GET', 'POST'])
def calculator():
    result = None

    if request.method == 'POST':
        expr = request.form['expression']

        try:
            result = eval(expr)
        except:
            result = "Error"

    return render_template('calculator.html', result=result)