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LESSON I.

NOTATION is writing numbers; Numeration is reading them. Numbers are written or expressed by words, by figures, and by capital letters.

The Arabic method of expressing numbers by figures is used in all arithmetical computations. Ten figures are used, viz., the figure one (1), the figure two (2), the figure three (3), the figure four (4), the figure five (5), the figure six (6), the figure seven (7), the figure eight (8), the figure nine (9), and the cipher (0); each of which expresses as many units as its name indicates. These ten figures are called the arithmetical lphabet.

The Roman method of expressing numbers by letters is used in numbering the chapters of books, sections, &c. Seven letters are used, viz., I, V, X, L, C, D, and M. The letter I expresses one; V, five; X, ten; L, fifty; C, one hundred; D, five hundred; and M, one thousand.

All numbers can be expressed by these ten figures, or seven letters, by combining and repeating them, which will be shown to some extent in the following lessons:

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