def approx_pi(throws)
  times_inside = throws.times.count {Math.hypot(rand, rand) <= 1.0}
  4.0 * times_inside / throws
end

[1000, 10_000, 100_000, 1_000_000, 10_000_000].each do |n|
   puts "%8d samples: PI = %s" % [n, approx_pi(n)]
end