Works here evry time. I made three different co-workers do it. They are a bit freaked out by the whole thing.

its rigged!!! the reference table changes everytime and when it didn't work the first time for whatever reason I kept clicking try again and didn't look at the symbol again cuzz I already knew what it was (or so I thought) but then I noticed the table changes every dang time. RIGGED I TELL U!!

I saw this on another forum about two weeks ago and the answer is always a multiple of 9 - so even though the symbols change for each number everytime you work it - all the numbers that are a multiple of 9 has the same symbol each time! IE, 9, 18,27,36,45 etc will always have the same symbol. The symbol will change each time but all multiple's of 9 will have the same symbol.