Mental arithmetic is a cognitive domain that remains comparatively stable during adulthood. While domain-general processes (e.g., working memory, inhibition, processing speed) decline with aging, specific arithmetic processes are largely preserved. In two studies, we investigated how aging affects arithmetic facts and procedures by comparing older (≥ 60 years) to younger (18 – 34 years) adults in addition and subtraction with vs. without carry/borrow procedures. The general pattern of arithmetic performance showed that older adults were slower than younger adults to solve the arithmetic problems but did not differ in accuracy. In single-digit arithmetic tasks, the carry and borrow effects did not differ between the age groups, as older adults retrieved the solutions of larger problems from memory while younger adults had to calculate them. Older adults were therefore able to compensate general slowing by relying on faster retrieval strategies. In two-digit arithmetic tasks, the carry and borrow effects were similar or even smaller in older compared to younger adults, indicating that procedures relying on the place-value system remain intact during aging. Moreover, younger and older adults do not differ in the underlying processes, as both rely on categorical and continuous, magnitude-based processing for the carry effect, while the borrow effect is mainly processed categorically. These results suggest a highly developed fact network for single-digit arithmetic and intact arithmetic procedures during aging. We conclude that the age-related general cognitive decline affects arithmetic in terms of general slowing but spares arithmetic facts and procedures.