[vignesh_m]

3.1536 - thats way to inaccurate to be of any interest imo. Even 22/7 is a way better approximation

[jaclaz]

Though nothing beats Milü in its simplictry and accuracy:

https://en.wikipedia.org/wiki/Milü

355/113: >An easy mnemonic helps memorize this useful fraction by writing down each of the first three odd numbers twice: 1 1 3 3 5 5, then dividing the decimal number represented by the last 3 digits by the decimal number given by the first three digits.