Somebody tell me how this works.
Update: I have lots of smart readers, or at least readers who are more clever than I am. The trick to the puzzle is that when you add the digits of a two digit number together and subtract them from the original number, you always wind up with a multiple of 9. The person who created the puzzle just assigns the same symbol to all multiples of 9, so it always shows the symbol for the number you’re “concentrating on.” The creator of the puzzle wisely shuffles the symbols every time you try again, so it’s not obvious what’s going on. Thanks to the many people who sent me the solution.