“Finding the money”—whether money lost, hidden, or needed—became a defining practical and epistemological problem in the decade after the 1688 Revolution. It was a problem that linked together actors in fiscal administration, parliamentary politics, and economic theory, and drove innovative new applications of numerical calculation to political reasoning. In the debates on monarchical revenues that arose in 1689, a crisis of knowledge engulfed Parliament as MPs discovered how few among them had any insight into the nation's fiscal well-being. A parliamentary Commission of Public Accounts, formed in 1690, learned that even a basic financial assessment was extraordinarily difficult. Yet the commission's travails also revealed numerical calculations to be a potent political tool, which empowered relative outsiders to make incisive criticisms without complete information. Such combative political computation was systematized in the “political arithmetick” of Charles Davenant, who provided a novel political rationale for the value of “probable” knowledge.