What is the fastest way to get the value of π?

Question

I\'m looking for the fastest way to obtain the value of π, as a personal challenge. More specifically, I\'m using ways that don\'t involve using #define constan

Answer 1

If you are willing to use an approximation, 355 / 113 is good for 6 decimal digits, and has the added advantage of being usable with integer expressions. That's not as important these days, as "floating point math co-processor" ceased to have any meaning, but it was quite important once.