Calculating and making public carbon footprints is becoming self-evident for multinational corporations. Drawing on ethnographic data I narrate of the calculative routine practices involved in that process. The narration shows how routine yet sophisticated mathematical transformations are involved in retrieving salient information, and second that mathematical consistency is readily interrupted by ‘dirty data’. Such interruptions call for opportunistic data management in devising work-arounds, which effect enough mathematical coherence for the number to hold together. Foregrounding an episode of calculative data retrieval, interruption and work-around contrivance, I employ it to make a comparative reading of two STS analytics, arguing: whereas Callon and Law’s analytic technique of qualculation reveals the episode of data management and work around contrivance as a teleologically oriented process that manages to bridge mathematical inconsistency, Verran’s technique of ontologising troubles enables us to recognise how a number-as-network configures its particular kind of certainty and coherence, how it sticks.