Its just a representation of a processor field called "adder", that add's  binary numbers. 

I made this after a while trying to figere out how to make the signals that come to the gates input arrive at the same time (if not, the result gets incorrect...). 

The 1st row is the 1st number, and the 2nd row is the 2nd number. The result is on the third row. Adding the numbers corresponding to the LEDs that light up will give the result in decimal. (this is how you convert binary to decimal)

Hope you like it =)

Edit: If you're interested in understanding how it works (what I think is very cool) this video is awesome: http://www.youtube.com/watch?v=VBDoT8o4q00