Find the largest prime factor of a composite number.

euler-003.rb

#!/usr/bin/env ruby
# Problem: Find the largest prime factor of a composite number.
# Description: The prime factors of 13195 are 5, 7, 13 and 29.
#
# What is the largest prime factor of the number 600851475143?

# Solution:

number = 600851475143

1.upto(number) do |i|
  x = i/2 if (number%i).zero?
  unless x.nil?
    if x.odd? || x < 1
      next
    else
      puts i
      break
    end
  end
end