π in Ruby
I think I'm pretty much doing pi approximations in every language now, so here it is in Ruby!
Here are the other approximations so far:
Java - https://repl.it/talk/share/p-in-Java/34978
QBasic - https://repl.it/talk/share/p-in-QBasic/34973
Fortran - https://repl.it/talk/share/p-in-Fortran/34890
APL - https://repl.it/talk/share/p-in-APL/34888
Forth - https://repl.it/talk/share/p-in-Forth/34652
LOLCODE - https://repl.it/talk/share/p-in-LOLCODE/34421
Python and Node.js (Node is linked in post) - https://repl.it/talk/share/2-Approximations-of-p-In-Only-Four-Lines-of-Code/32773
C - https://repl.it/talk/share/p-Approximations-in-C/33461
Credit to @TheForArkLD , @Warhawk947 , and @LizFoster for inspiring these approximations. Most of these use the Nilakantha Series, although I also use the arctangent method (multiplying the radian arctangent of 1 by 4 to get pi and getting the arctangent with an infinite series) in three of them (Python, Node, and C).
And for pi, it is clearly the best mathematical constant that exists and I really enjoy math, so, my fascination with pi is simply derived from my interest in math.