Newton's Formula for Pi

Theorem
$\pi$ (pi) can be approximated using the formula:
 * $\pi = \dfrac {3 \sqrt 3} 4 + 24 \left({\dfrac 1 {12} - \dfrac 1 {5 \times 2^5} - \dfrac 1 {28 \times 2^7} - \dfrac 1 {72 \times 2^9} - \cdots}\right)$