2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/75933This is a paper which present a mnemotechnical method that we call LAC for Lists, Arrangements and Combinations. It can help students or any one to recollect formulae from combinatorial theory ([1],[2],[3],[4]) without an a priori memorization of them.Combinatorics03E04;05A19; 97D40; 97D99text