2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/160825Stirling's formula, the asymptotic expansion of $n!$ for $n$ large, or of $Γ(z)$ for $z\to \infty$, is derived directly from the recursion equation $Γ(z+1) =z Γ(s)$ and the normalization condition $Γ({1/2}) =\sqrtπ$.4 pages; omitted second author addedCombinatorics33B15; 11B37text