2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/209497We prove that a positive integer not of the form, 4^{k}(8m+7) can be expressible as a sum of three or fewer squares by using some results of Kane and Sun on mixed sums of squares and triangular numbers.Number TheoryCombinatorics05A17, 11D45, 11D85, 11E25, 11P83text