>way cool! How do they do that?
If you don't want to know how this is done, don't read this reply.
Here's how they do it. If you follow those directions regarding the two-digit number and subtract the sum of those digits, the result will always be a number that is a multiple of nine. If you look at the chart, you will see that the symbol is the same for all multiples of nine. All of the symbols on the chart change each time you play, but the symbols associated with multiples of nine will match.
It is a fun game to play, though. Hope I didn't spoil it for anyone.
MissL