The Amazing Mind Reader

[PayItForward]

Using that calculation on any number between 10 and 99 will always return either:-

9
18
27
36
45
54
63
72
81

If you look at the chart.
All the symbols corresponding to the above numbers are the same symbol.
QED

PS. I checked the calculation using an excel spreadsheet as I can't do all this maths in my head.

PPS. Every time you hit the 'Try again' link it moves the symbols around on the chart, so you get a new symbol in the ball. But this new symbol is the same on the above core of numbers for that turn of the puzzle. Very Clever.