The rule is: take any two-digit number with ten different numbers, exchange it with the ten-digit number to get another two-digit number, then subtract the smaller one from the larger one to get the difference, and repeat the previous operation. The final difference is nine times the difference between the ten digits and each digit (the big one MINUS the small one).

Extended data:

Algorithm is an algorithm abstractly summarized by observing, comparing and analyzing some equations. It is not only an important mathematical law, but also an inherent property of mathematical operation. Including additive commutative law and associative law, multiplicative commutative law and associative law, and the distribution law of multiplication to addition.