a. (and sb.) [f. L. arithmētic-us, a. Gr. ἀριθμητικ-ός numeric (see ARITHMETIC) + -AL.]
A. adj. Of, pertaining to, or connected with, arithmetic; according to the rules of arithmetic. Arithmetical mean, progression, proportion: see quot.
1543. Recorde, Gr. Arts (1646), 299. The reasons of works Arithmeticall.
1594. Blundevil, Exerc., I. xiii. 39. Arithmeticall Progression … is that which proceedeth by like difference of quantity, as thus; 3, 5, 7, 9, 11, 13.
1660. R. Coke, Justice Vind., 23. As 3. 4. 5. 6. are in Arithmetical proportion, for they increase equally; and 3. added to 6. is equal to 4. added to 5.
1798. Hutton, Course Math. (1810), I. 114. To find an Arithmetical Mean … Add the two given extremes or terms together, and take half their sum.
1855. Macaulay, Hist. Eng., IV. xix. 327. In the face of arithmetical demonstration.
B. as sb. A number in an arithmetical progression.
1798. Hutton, Course Math. (1827), I. 123. The sum of the extremes is equal to double the mean, which is the property of arithmeticals.
