Data (Schoen et al. 2016) suggests that because many students' understanding of subtraction is limited by thinking about the operation only as take-away or by using a default procedure, such as the standard subtraction algorithm in the United States, second graders are much more likely to solve 100 minus 3 correctly than 201 minus 199. This article argues the importance of students learning to reason flexibly about subtraction. The authors highlight a useful but often ignored way of reasoning, and offer suggestions for teaching about subtraction.