MENTAL ARITHMETIC;

OR,

A CONCISE SYSTEM

OF

COMMERCIAL ARITHMETIC,

BY

JAMES STRACHAN, F.E. I. S.,

TEACHER OF ARITHMETIC, &c., MILNE'S FREE SCHOOL,
FOCHABERS, AUTHOR OF "INTRODUCTION TO

ARITHMETIC, &c., &c.

First Chousand.

LONDON:

SIMPKIN, MARSHALL, & Co.

EDINBURGH:

OLIVER & BOYD. ABERDEEN: LEWIS SMITH,

SOLD BY ALL Booksellers.

1852.

(Price 2s. 6d. Bound.)

181. c. 52;

ENTERED AT STATIONERS' HALL.

ΤΟ

HIS GRACE THE DUKE OF RICHMOND,

CHANCELLOR OF MARISCHAL COLLEGE, ABERDEEN,

AND PRINCIPAL DIRECTOR OF MILNE'S

FREE SCHOOL, FOCHABERS.

MY LORD DUKE,

Availing myself of the permission so

kindly given, I now beg leave most respectfully to dedicate

to your Grace this little Work on Mental Arithmetic.

And, I have the honour to be,

MY LORD DUKE,

Your Grace's much obliged,

And very humble Servant,

JAMES STRACHAN.

INTRODUCTIO N.

THE study of MENTAL ARITHMETIC is but little attended to in most of our Educational Institutions in Scotland, and, notwithstanding the many excellent works now published on Arithmetic, few of them treat of this branch of the Science as its importance deserves, and this is, it may be presumed, one reason that it has not been more generally introduced as a part of the regular routine in the Study of Arithmetic.

It is well known to every one in business, that a shorter method of computing is indispensable, than that with which the youth, who has just finished his arithmetical studies, is acquainted; hence every one is entirely left to contrive for himself some more expeditious method of computing; the method thus acquired will, in all probability, be kept as a secret or mystery. Now, were the study of Mental Arithmetic more generally attended to in schools, young men would be found much better qualified for entering the shop, counting-house, bank, or any other situation where expertness in calculating is an essential recommendation. Nor is it only to those so employed that a knowledge of Mental Arithmetic is of any importance, there being few, if any, of either sex in any situation to whom a short and simple method of calculating will not at times be of considerable importance, as many occasions occur when there is neither time nor means at hand for the ordinary tedious methods.

It is with a view to facilitate the study of this branch of the Science of Arithmetic that the following pages have been prepared, not only to furnish a simple and concise system of Mental Arithmetic, but also methods by which computations may be performed more expeditiously and with less risk of error than by the common rules.

Fochabers, 1852.

J. S.