We will be dealing with two-digit numbers non divisible by 11.
For each such number A there will exist another A’, a number created by inverting the digits of A so 45’=54, 87’=78.
Take for example 2 numbers 36 & 84: their product is the same as the product of those numbers inverted i.e. 63*48.

Find all the couples possessing such feature i.e. AB=(A')*(B').
Rem: to preserve conformity present the smallest number on the LHS of the equation - like 12*42=21*24.

Edited on July 23, 2024, 6:58 am

Posted by Math Man on 2024-05-27 19:06:31