ELEMENTS

OF

ARITHMETIC.

LONDON:

PRINTED BY THOMAS DAVISON, WHITEFRIARS.

THE

ELEMENTS

OF

ARITHMETIC.

BY

AUGUSTUS DE MORGAN,

PROFESSOR OF MATHEMATICS IN THE UNIVERSITY OF LONDON.

"Ce n'est point par la routine qu'on s'instruit, c'est par sa propre
réflexion; et il est essentiel de contracter l'habitude de se rendre raison de
ce qu'on fait: cette habitude s'acquiert plus facilement qu'on ne pense; et
une fois acquise, elle ne se perd plus."

CONDILLAC.

LONDON:

PRINTED FOR JOHN TAYLOR,

BOOKSELLER AND PUBLISHER TO THE UNIVERSITY OF LONDON,
30, UPPER GOWER-STREET.

1830

189.

PREFACE.

THIS little work is an attempt to give the young student the common rules of Arithmetic, accompanied by the reasoning to which he must habituate his mind before he can make progress in any science.

I might speak from experience, of the nature of the arithmetical knowledge which most youths acquire before they commence the study of Geometry and Algebra. But as almost all agree in opinion, that this science ought not to be, as it is in this country, degraded into a mass of rules learned by rote, one half of which are of no use but in commercial business, and rarely even there, I will proceed to make a remark on the manner in which this book should be studied.

In order to avoid the generalities of algebraic language, which the mind of a beginner cannot grasp, it is necessary to confine each

b