Did you know they had math back in the Stone Age? You task is to add the stones with the numbers that are coming down to get the number on the right. There are many levels of the game, the number is different each time, as well as the speed the numbers are coming down with.
I guess, this game should be given by prescription - it is indeed very useful for the brain!
Play Stone Age online, add it to bookmarks - you'l love it!