Solution: Google Labs Aptitude Test

start_time = Time.now 
(1..9).each do |w|
  (1..9).each do |d| 
    next if d==w
    (0..9).each do |o| 
      next if o==d || o==w
      (1..9).each do |t|
        next if t==o || t==d || t==w
        (0..9).each do |g|
          next if g==t || g==o || g==d || g==w
          (0..9).each do |l|
            next if l==g || l==t || l==o || l==d || l==w
            (0..9).each do |e|
              next if e==l || e==g || e==t || e==o || e==d || e==w
              (0..9).each do |c|
                next if c==e || c==l || c==g || c==t || c==o || c==d || c==w
                (0..9).each do |m|
                  next if m==c || m==e || m==l || m==g || m==t || m==o || m==d || m==w
                  top_no =    w*100000 + w*10000 + w*1000 + d*100 + o*10 + t
                  bottom_no = g*100000 + o*10000 + o*1000 + g*100 + l*10 + e
                  result =    d*100000 + o*10000 + t*1000 + c*100 + o*10 + m
                  if top_no - bottom_no == result
                    puts "#{top_no} - #{bottom_no} = #{result}"
                  end
                  
                end 
              end
            end 
          end
        end 
      end
    end 
  end
end
puts "Time to solve: #{Time.now - start_time}"