 with a being any quantity (aliqua quantitas) and m any natural number greater than or equal to 2 (cf. Murdoch 1964; Mazet 2003). He informs us that we have to take the difference of two successive terms, that is \(a/m^n - a/m^{n+1}\), and divide it through the first of these terms, that is \(a/m^n\), so that we get: