Write 3-digit number whose 1st digit differs from last by 1. Reverse the digits and subtract smaller from larger one.

Question

Write any three-digit number whose first digit differs from its last by 1. For instance 627 or 506. Reverse the digits then subtract the smaller from the larger number. Do this with several numbers. What do you notice? Does this always happen?

Answer 1

The difference is always 99 whatever is the number.

Example
847 - 748 = 99