a. Obs. rare. [ad. mod.L. summātōrius, f. med.L. summāt-: see SUMMATE and -ORY.] Summatory arithmetic, calculus: see quots.
1704. C. Hayes, Treat. Fluxions, 60. The fundamental Rule in Summatory Arithmetick, to find the Flowing Quantity of a given Fluxion.
1710. J. Harris, Lex. Techn., II. Summatory Calculus, according to some, is the same with the Calculus Differentialis of Leibnitz; but more properly Summatory Arithmetick, is the Art of finding the flowing Quantity, from the Fluxion.
