Mathematical problem-solving places heavy demands on children's developing working memory capacity. This review examines how offloading numerical information using embodied (e.g. finger counting) or external tools (e.g. manipulatives) can reduce cognitive load and improve mathematical task performance. Strategic offloading emerges in childhood; however, it is less often observed in children with lower working memory or mathematics ability. Scaffolding and encouraging children's use of cognitive offloading strategies may promote mathematical competency.