how to apply formula in flask python code example

Example 1: simple flask app

# Extremely simple flask application, will display 'Hello World!' on the screen when you run it
# Access it by running it, then going to whatever port its running on (It'll say which port it's running on).
from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, World!'

if __name__ == '__main__':
    app.run()

Example 2: python render_template

from flask import Flask
from flask import render_template
app = Flask(__name__)

@app.route('/')
def index():
   return render_template("index.html") #if you want to render a .html file,
                        # import render_template from flask and use
                        #render_template("index.html") here.

if __name__ == '__main__':
    app.debug = True
    app.run() #go to http://127.0.0.1:5000/ to view the page.