MATHEMATICAL TEXT-BOOKS By G. A. WENTWORTH, A.M. Mental Arithmetic. GRAMMAR SCHOOL ARITHMETIC BY G. A. WENTWORTH, A.M., AUTHOR OF A SERIES OF TEXT-BOOKS IN MATHEMATICS. REVISED EDITION. BOSTON, U.S.A.: 1897. Entered, according to Act of Congress, in the year 1889, by G. A. WENTWORTH, in the Office of the Librarian of Congress, at Washington. ALL RIGHTS RESERVED TYPOGRAPHY BY J. S. CUSHING & Co., Boston, U.S.A. PRESSWORK BY GINN & Co., Boston, U.S.A. PREFACE. THIS age an intelligent knowledge of the subject and a moderate power of independent thought. Whether Arithmetic is studied for mental discipline or for practical mastery over the every-day problems of common life, mechanical processes and routine methods are of no value. Pupils can be trained to logical habits of mind and stimulated to a high degree of intellectual energy by solving problems adapted to their capacities. They become practical arithmeticians, not by learning special business forms, but by founding their knowledge on reasoning which they fully comprehend, and by being so thoroughly exercised in logical analysis that they are independent of arbitrary rules. The book contains a great number of well-graded and progressive problems, made up for youths from ten to fourteen years of age. Definitions and explanations are made as brief and simple as possible. It is not intended that definitions shall be committed to memory, but that they shall be simply discussed by teacher and pupils. Every teacher, of course, will be at liberty to give better definitions, and to make a better presentation of methods, than those given in the book. In short, the chief object in view will be gained if pupils are trained to solve the problems by neat and intelligent methods, and are kept free from set rules and formulas. A great many number-problems are given in the first pages of the book, so that the necessary facility and accuracy in computing |