Write your code to calculate pi as accurate as you can

Question

Write a mathematical formula you use then attach a code which executes your formula.

Answer 1

You would need a library which can handle the massive amount of digits this formula produces to really use the algorithm ^^
https://code.sololearn.com/cJ0s82a3cb2B/?ref=app

Answer 2

https://code.sololearn.com/cUGHRx5t8csQ/?ref=app

or

http://users.telenet.be/koen.beek/pages/formules.htm

Answer 3

More accurate (5 digits after floating point), and quickest:

https://code.sololearn.com/cGkU7PO5ozF4/?ref=app

Answer 4

in javascript
document.write(Math.PI);