I've seen and already explained it once, about 6 months ago. It all has to do with math, as stated above. here is how it works. The symbols are the same, they just rotate them to a certain degree. Now, if you want to know how it works... then do the following, just add the numbers they say in your head and do the subtraction like they said. You will notice that no matter what, the SAME symbol will appear everytime. Now, the next time it is done the symbols change location so a different symbol is shown, but the math is the same. Its really quite easy.