euler 6

!#/usr/bin/ruby
max = 100
sum = (0..max).inject { |s,n| s + n**2 }
sqr = ((0..max).inject { |s,n| s+n }) ** 2
puts sqr-sum

###### Alternate solution :


#!/usr/bin/ruby
require 'mathn'
n = 100
puts "Difference is #{ (n * (n**2 - 1) * (n / 4 + 1 / 6)).abs }."