Flash Mind Reader....try this

[barrett7890]

it doesn't matter what you pick next it should always pick the right symbol, every possibly answer each time will have the same symbol

cami
x

 

[Muffin]

i.e. when I tested the theory by picking a number that would yield the same answer--it didn't pick the right picture.

The only possible answers you can get are all multiples of 9 (9, 18, 27, 36, 45, 54, 63, 72 or 81). If you got some other number, your math was incorrect.