Have you seen this before - its weird... how does it do it?
http://trunks.secondfoundation.org/files/psychic.swf

Whatever number you come up with by doing as they say, the symbol will be the same.You can check by in your head doing 2or 3 calculations and looking it up in the grid -you'll find all answers has the same symbol. Then if you try again after having clicked all the symbols have changed but it will still be the same one (but different one to last time) for whatever number you calculate, so it just LOOKS like it knows.

I knew there had to be a method to it.. just couldnt work it out!!