Forty young adults, 40 healthy older adults, and 23 probable AD patients were asked to solve simple subtraction problems (e.g., 9-3; 14-9) in a choice condition and in a no-choice condition. Participants could choose between retrieval and non-retrieval strategies on each problem in the choice condition and were required to use retrieval on all problems in the no-choice condition. Results showed that arithmetic performance and strategy use were influenced by problem, participant, and strategy characteristics. Age-related differences were found in strategy use and strategy execution. Dementia-related differences were found in strategy execution, but not in strategy selection. AD patients had poorer performance (i.e., larger response times and percent of errors) than age-related controls, with especially low accuracy under no-choice condition. The findings have implications for our understanding of aging effects in arithmetic, strategic variations in Alzheimer's patients, and sources of cognitive decline during early stages of Alzheimer's disease (AD).