Number sense is the basis of arithmetic and algebra, but counting dominates instruction, and fine-grained explorations of what children "do" as they develop number sense are relatively rare. Conceptually congruent actions that align with the mathematics support learning, and multitouch technology can afford using these actions while developing number sense. Therefore, this study investigates development of number sense, especially strategies and gestures, as 30 kindergartners interact with a multi-touch mathematics app designed to encourage subitizing. Findings reveal dominance of counting strategies, gesture patterns, and potential disconnects among representations. Together, they add to concerns about the dominance of counting in instruction, suggest that composition and subitizing warrant increased attention, and emphasize the relevance of gestures for revealing and developing number sense.