[chris_overseas]

This is explained in the second paragraph:

> Yee independently verified the calculation using Bellard's formula[0] and BBP formula[1]

[0] https://en.wikipedia.org/wiki/Bellard%27s_formula

[1] https://en.wikipedia.org/wiki/Bailey%E2%80%93Borwein%E2%80%9...

[audiometry]

Disappointed the Wikipedia article didn’t explain how in the world they arrived at that formula, why it even works. This type of stuff is pure magic to me.

[aboutruby]

There is a proof linked from the Wikipedia article: https://www.davidhbailey.com/dhbpapers/digits.pdf

[mhh__]

https://bellard.org/pi/pi_bin.pdf