The Question and Answer Board

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There's no real "trick" involved, just simple math. When you take a two digit number, add the digits together and subtract the sum from the original number there are only so many answers. Specifically, 9, 18, 27. 36, 45, 51, 54, 63, 72, 75, and 81. As long as the "mystic" makes sure all those numbers have the same symbol next to them it is easy to guess what the mystic symbol is.

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