Young and older adults solved complex addition problems such as 49 + 56. Verbal protocols, solution times, and percentage errors documented strategy repertoire and strategy selection in young and older participants and age-related differences in complex arithmetic performance. Both young and older adults used a set of 9 strategies to solve complex addition problems, although many older adults used a smaller strategy repertoire. The data also showed age-related differences in strategy execution and strategy selection. We discuss general implications of the present data to further our understanding of complex arithmetic and the role of strategic variations during aging.