Why Does Thios Work?

[The Dad Fisherman]

The symbols change after every guess. so mathematically it always defaults to just one symbol.

Do the same # twice....the symbol will be different each time.

Also do the math from three different 2-digit #'s before clicking the ball and they will always be the same symbol

[Basser]

For the math problem given there are only the following possible answers 9,18,27,36,45,54,63,72,81. The symbol after those particular numbers will always be the same even though they are changed after each "spin" of the blue ball...The blue ball only has one symbol behind it for each "spin"..the "correct" one.