2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/70721Let $K$ be a global field and $n > 1$ an integer. We show $n$ is composite if and only if there is an irreducible polynomial $f(x) \in K[x]$ of degree $n$ which is reducible $q$-adically for all the primes $q$ of $K$.Number Theorytext