Estimate pi using random points and the distance formula

pi.rb

#!/usr/bin/env ruby
#
# Estimate pi using 1 random point:
# ./pi.rb 1
#
# Estimate pi using 1000 random points:
# ./pi.rb 1000

class Point
  def initialize
    @x = rand
    @y = rand
  end

  def inside?
    Math.sqrt(@x**2 + @y**2) < 1
  end
end

count = ARGV.shift.to_i
sum   = 0

count.times do
  sum += 1 if Point.new.inside?
end

puts (sum.to_f / count) * 4