Monte-Carlo Pi

[Albert Chan]

Probability of random()/random() rounded to even integer = 1 + 1/4 - PI/4 = (5-PI)/4 ≈ 0.4646

Or, we can count odd's:
Probability of random()/random() rounded to odd integer = (PI-1)/4 ≈ 0.5354

lua> s, n = 0, 5e6
lua> for i=1,n do s = s + round(random()/random())%2 end
lua> s/n
0.5354442

see https://www.hpmuseum.org/forum/thread-13...#pid129470