Alain Desrosières understood statistics as simultaneous representations of the world and interventions in it. This article examines two mechanisms that mediate how numbers do both. The first, reverse engineering, describes how working backwards from a desired number shapes organizational routines. The second, emotional attachment, describes the processes by which numbers generate a variety of emotions that sometimes stimulate collective identities. Focusing on educational rankings but including examples of other types of numbers, it argues for the importance of disclosing the effects of specific causal mechanisms in the analysis of particular performance measures.