Math and Psyche

The following flash was created by Andy Naughton.

Choose any two digit number, add together both digits and then subtract the total from your original number.

When you have the final number look it up on the chart and find the relevant symbol. Concentrate on the symbol and when you have it clearly in your mind click on the crystal ball and it will show you the symbol you are thinking of.

Andy note: The Mind Reader always works if you follow the instructions properly. If you get the wrong symbol this means that you did not follow the instructions properly or you did the maths incorrectly. We suggest you try again, it may help to improve your basic mathematics skills.

Solution

Every possible result of the above operation has to be a multiple of nine

10a + b – (a + b) = 9a

and should be one of the following number:

9, 18, 27, 36, 45, 54, 63, 72 or 81.

Every time after you clicked and every time you refresh the screen the symbols change.
But please note that the glyphs of all the above numbers are the same allways! So the “program knows” which symbol will be selected by you before you do the operation!

So we may reverse the task. If we find the symbol next to the above numbers, without all counting and concentrating we can tell what glyph will be showed by the magic sphere when we click on it!