Lena is developing a small helper for the ReviewThat Labs dashboard to reconcile customer account balances stored in an older, segmented format. Because the legacy system saves digits in reverse order across separate data nodes, she needs a reliable way to add these sequences together and produce a single combined result. Mark suggested she build this as a reusable utility to help the team with future data migrations. As an example, if the tool receives one sequence of 2-4-3 and another of 5-6-4, it should correctly calculate and return the sum as 7-0-8.