In 2017, it was excitedly pronounced across major newspapers in Australia that public schools' share of student enrolment had increased, marking a "determined end to a 40-year decline". The claims were bolstered by numerical data, and an accompanied media release, issued by the Australian Bureau of Statistics. These bold claims immediately caught my attention, first for the assertion they were making and the implications for public schools; but second, for the way in which they potentially elided complex and variable units of analysis, to simplify and stabilise the numbers into a depoliticised narrative. Education reform relies on measurements, quantification and statistics to inform policy, but also to inform public opinion. Drawing on Petty's notion of political arithmetic and Gorur's "sociology of measurement", this paper explores and critiques the role of counting in relation to national school enrolment shares, as divided between public and private schools in Australia.