#! usf/local/bin/ruby

def pi(n)
  (10**n).times.reduce(0) { |r, i| r + (-1.0)**i / (2 * i + 1) }
end

def time
  start = Time.now
  result = yield
  diff = Time.now - start
  puts "Elapsed time: #{diff} sec"
  p result
end

time { pi 8 }