2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/128536We investigate the classical Zassenhaus conjecture for the unit group of the integral group ring of Mathieu simple group M23 using the Luthar-Passi method. This work is a continuation of the research that we carried out for Mathieu groups M11 and M12. As a consequence, for this group we confirm Kimmerle's conjecture on prime graphs.9 pages, updated bibliography and corrected part (i) of the TheoremRings and AlgebrasRepresentation Theory16S34; 20C05; 20D08text