div_vs_mod_vs_odd.rb

#!/usr/bin/env ruby

require 'benchmark'

count = 10e6.to_i

Benchmark.bm do |x|
  x.report(:mod) { count.times { |n| n % 2 == 0 } }
  x.report(:and) { count.times { |n| n & 1 == 0 } }
  x.report(:odd) { count.times { |n| n.even? } }
end

#        user     system      total        real
# mod  0.780000   0.000000   0.780000 (  0.775271)
# and  0.740000   0.000000   0.740000 (  0.735793)
# odd  0.650000   0.000000   0.650000 (  0.659626)