In three experiments, we investigate aging effects on approximate quantification. In all studies, young and older adults had to determine numerosities of black dots displayed in square grids. Participants reported their solution strategy after each trial. Eye-movements, trial-by-trial verbal reports, accuracy, and latency were recorded. Converging evidence from these different measures revealed following main results: (a) both young and older participants used five different strategies to estimate numerosities (Exp 1), (b) these strategies exhibited different patterns of speed, accuracy, and eye-movements, (c) surprisingly, when participants had to use a forced strategy, there were no differences between young and older adults (Exp 2), and (d) older adults chose strategies much less systematically and adaptively. These results have implications for further understanding approximate quantification skills and age-related differences in these skills. We discuss these implications.