Infinite Sets of Solutions and Almost Solutions of the Equation N ⋅ M= reversal(N⋅M)

Motivated by their intrinsic interest and by applications to the study of numeric palindromes and other sequences of integers, we discover infinite sets of solutions and almost solutions of the equation N？⋅？M=reversal (N？⋅ M). Most of our results are valid in a general numeration base.