Formula \:to\: calculate \:the \:numerical\: value \:of \:\:\:\pi

$ \sum_{n=1}^{∞}{\frac{\left( -1  \right)^n }{2n+1} =\frac{\pi}{4}} $
$ ⇒\pi=4\sum_{n=1}^{∞}{ \frac{\left(  -1 \right) ^n}{2n+1}}$

n = 295 (slider from 1 to 90000000000, step 1)