the last of the radical numbers or characters; from the combination of which any definite number, however large, may be produced. "It is observed by arithmeticians (says Hume), that the products of 9 compose always either 9 or some lesser products of 9, if you add together all the characters of which any of the former products is composed: thus of 18, 27, 36, which are products of 9, you make 9, by adding 1 to 8, 2 to 7, 3 to 6. Thus 369 is a product also of 9; and if you add 3, 6, and 9, you make 18, a lesser product of 9." See Hume's Dialogues on Nat. Relig. p. 167, 168, &c. 2d edit.