Holy Crap! I tried it many many times, and tried fooling it ... I can't for the life of me figure out how it works... it's gotta be a mathmatical thing, but it's way beyond me! Any Wizards out there know how this thing works???
Robert is right.
There are only certain numbers that you will get by calculating the way you are asked to
For example - 41: 5 - 36, 42: 6 - 36, 43: 7- 36, a.s.o, so if you choose a number between 41 and 49 the result is always 36.
So out of the 99 there are only a few that are the result of the calculation and they all have the same symbol.