odd_even_challenge.rb

class Fixnum

  def even?
    num = self
    stack = [1]
    while(stack.last < num)
      stack.push(stack.last*2) 
    end
    while(num > 1) 
      val = stack.pop 
      num -= val if val <= num
    end
    num == 0
  end
  
  def odd?
    !even?
  end

end

puts 1000.even?