Project Euler 33

gistfile1.rb

ans = Rational(1, 1)
(1..9).each do |a|
  (1...a).each do |b|
    (1..9).each do |c|
      d = Rational(b,a)
      if Rational(b*10+c, a*10+c) == d ||
         Rational(b*10+c, a+c*10) == d ||
         Rational(b+c*10, a*10+c) == d ||
         Rational(b+c*10, a+c*10) == d
         ans *= d
      end
    end
  end
end
puts ans.denominator # 100