What is the principle of the magical mind-reading handed down by gypsies?

Because the number you choose is designed by it, it is a "mind reading" to ensure that the patterns of these numbers are the same, and display the patterns represented by these numbers on the crystal ball, as follows:

Suppose you randomly choose a two-digit number, one digit is X and the other digit is Y, then this arbitrary number is10y+X.

Now subtract the sum of one digit and ten digits from any number you choose, that is, 10y+x-x-y=9y, which is a multiple of 9.

Since the arbitrarily selected number is two digits, the value of y can only be 1, 2, 3, 4, 5, 6, 7, 8, 9. So your final answer must be 9, 18, 27, 36, 45, 54, 63, 72, 865438+.

As long as the numbers in the chart (9, 18, 27, 36, 45, 54, 63, 72, 8 1) are the same, display this number with a crystal ball. Take a closer look, although the numbers in the chart have changed, 965438+.