Gypsy crystal ball mind reading

This is indeed a mathematical mystery, not a real mind-reading. First of all, look at the conditions he gave you-"a double digit"! The range of units is "1~9", and the range of ten digits is "0~9"!

Choose from 10~99, with ten digits represented by "10n" and one digit represented by "m" (the range of n is "1~9", the range of m is "0~9", and both n and m are integers! )

So,

The number selected from "10~99" is "10n+m"; One digit plus ten digits means "n+m"

"Add the ten digits and one digit of this number, and then subtract this sum from any selected number" means "(10n+m)-(n+m)", and the result is "9n"!

The final number should be an integer multiple of 9. Since the value range of n is "1~9", the result should be any one of "9, 18, 27, 36, 45, 54, 63, 72, 8 1"!

Pay attention to the chart he gave you. The numbers should be the same!

That is to say, no matter which number you choose within his given range, according to his requirements, the final result should be an integer multiple of 9 (that is, any of those numbers)!

But all the numbers corresponding to integer multiples of 9 (except 90, 99) are the same! Therefore, the display will definitely be that graphic!

In addition, according to the rules of the game he gave you, the final figure can't be "90,99" (because the final difference is "9n" and the range of N is "1~9"), so it doesn't matter if the figures corresponding to 90 and 99 are different from the other nine special figures!