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THE

YOUTH'S ASSISTANT

IN

THEORHETIC AND PRACTICAL

ARITHMETIC;

DESIGNED FOR THE USE OF

SCHOOLS IN THE UNITED STATES,

BY ZADOCK THOMPSON, A. M,
Author of the Gazetteer of the State of Vermont.

SIX TH EDITION.

Burlington:
E D W A R D SMITH.

1832.

The following explanations and table, not being contained in the Written Arithmetic, are inserted here for the convenience of those who have not studied the Mental Arithmetic. =EQUALITY is expressed by two horizontal marks; thus 100 cts.

1 dollar, signifies that 100 cents are equal to one dollar. +ADDITION is denoted by a cross, formed by one horizontal and one

perpendicular line, placed between the number; as 4+5=9,

signifying that 4 added to 5 equals 9. X MULTIPLICATION is denoted by a cross, formed by two oblique

lines placed between the numbers; as 5 x 3=15, signifying that

5 multiplied by 3, or 3 times 5 are equal to 15. --SUBTRACTION is denoted by one horizontal mark, placed between

the numbers; as 7-433, signifying that 4 taken from 7 leave 3. )( or ;Division is denoted three different ways; 1st. by the re.

versed parenthesis ; 2dly. by a horizontal line placed between the numbers with a dot on each side of it; and 3dly. by writing the number to be divided over the other in the form of a fraction; thus 2)6(3, and 6+2=3 and =3, all signify the same thing, namely that if 6 be divided by 2 the quotient is 3.

MULTIPLICATION AND DIVISION TABLE.

11 21 31 41 51 61 71 81 9 | 10 | 11 | 12
2 4 6 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 24
3 6 9 | 12 | 15 | 18 | 21 | 24 | 27 30 33

36
4 8 | 12 | 16 20 24 28 32 36 40 44 48
,5 | 10 | 15 20 25 30 35 40 45 50 55 60
6 | 12 | 18 | 24 | 30 | 36 | 42 | 48 54 60 66 72
|

63 70 77 84 8 1624 | 32 | 40 48 56 64 72 80 88 96 9] 18 27 36 45 54 63172 81 90 99 | 108 10 20 30 40 50 60 70 80 90 100 110 120 11 | 22 | 33 | 44 | 55 | 66 | 77 | 88 99 | 110 | 121 | 132 12 | 24 | 36 | 48 | 60 | 72 | 84 | 96 | 108 | 120 | 132 | 144

Entered according to Act of Congress, in the year one thousand might hundred and twenty eight,' by ZADOCK THOMPSON, in the Clerk's Office of the District of Vermont.

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(To the fourth edition. )

WHEN the improved edition of this work was published, in 1828, it was intended that the Written Arithmetic, which forms the second and third parts should always be accompanied by the Mental Arith. metic embraced in the first part. Since that time it has, however, been thought best to transpose such tables from the Mental to the Written Arithmetic, as to render the latter complete without the former, in order to lessen the expense of the book to those who do not wish to study mental arithmetic, or who have studied some other treatise ; and, thus prepared, it is now presented to the public. No alteration has been made from the last edition in the arrange. ment of the rules, and the whole of the second part is presented, as before, on the inductive plan of Lacroix. The principles are first developed by the analysis of familiar examples, and the method of applying these principles to the solution of questions is then ex. pressed in general terms, forming a Rule, which is still further illustrated by a great variety of practical questions. The analysis is printed in small type, occupies but little space, and may be omitted by those who wish to use rules without understanding them.

Addition and Multiplication, both involving the same principles, are presented in connexion, and also Subtraction and Division. A knowledge of decimals being necessary to a good understanding of our Federal currency and this knowledge being easily acquired by such as have learned the notation of whole numbers, decimals and Federal money are introduced immediately after the first section on simple numbers. By acquainting the pupil thus early with dicimals, he will be likely to understand them better and to avail himself of the facilities they afford in the solution of qnestions and the transaction of business.

Reduction ascending and descending are arranged in parallel columns and the answers to the questions of one column are found in the corresponding questions of the other. Compound multiplica. tion and division are arranged in the same way, and only one general rule for each is given, which was thought better than to perplex the pupil with a multiplicity of cases.

Interest and other calculations by the hundred are all treated decimally, that method being most simple and conformable to the notation of our currency. The nature and principles of proportion are fully developed and the method of applying them to the solution of questions clearly shown.

The written arithmetic of fractions being, to young pupils, some. what difficult to be understood, is deferred till they are made fa. mlliar with the most important arithmetical operations performed with whole numbers and decimals. The nature of roots and powers has been more fully explained in the present edition, and several now diagrams introducod for their elucidation. Throughout the

second part, it has been our main object to familiarize the pupil
with the fundamental principles of the science, believing that
when these are well understood, he will find no difficulty in applying
them to the particular cases which may occur.

The third part is mostly practical, and composed of such rules
and other matters as we conceived would be interesting and useful
to the student and the man of business.

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98

MENSURATION

64 Mensuration of Superficies 132

Compound Interest

67 Mensuration of Solids

136

Discount

68 SECT. III.-PHILOSOPHICAL

Loss and Gain

69

MATTERS

138

Equation of Payments

70 Fall of Heavy Bodies

138

SECT. VI.--PROPORTION

72 Pendulums

141

Single Rule of Three

74 Mechanical Powers

142

Double Rule of Three

78 SECT. IV. MISCELLANEOUS

Fellowship

80

QUESTIONS

144

Alligation

81 SECT. V.-PRACTICAL RULES

Assessment of Taxes

86

AND TABLES

148

SBCT. VII.-FRACTIONS

88 Table of Cylindric Measure 149

Definitions

89 Table of Square Timber Measure 150

Integers treated as Fractions 90 Log Table-Log Measure 153

Multiplication and Division of Fr. 91 Log 1.ble--Board Measure 154

Multiplication by Fractions 92 SECT. VI.-BOOK KEEPING 155

Division by Fractions

PRACTICAL FORMS.

164

Fractions changed to other Fr. 94

62

PART II.

WRITTEN ARITHMETIC.

SECTION I.

NOTATION AND NUMERATION,

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70. An individual thing taken as a standard of compari Bon, is called unity, a unit, or one.

71. Number is a collection of units, or ones.

72. Numbers are formed in the following manner; one and one more are called two, two and one, three, three and one, four, four and one, five, five and ono, six, six and one, seven, seven and one, eight, eight and one, nine, nine and one, ten; and in this way we might go on to any extent, forming collections of units by the continual addition of one, and giving to each collection a different name. But it is evident, that, if this course were pursued, the names would soon become so numerous that it would be utterly impossible to remember them. Hence has arisen a method of combining a very few names, so as to give an almost infinite variety of distinct expressions. These names, with a few exceptions, are derived from the names of the nine first numbers, and from the names given to the collections of ten, a hundred, and a thousand units. The nine first numbers, whose names are given above, are called units, to distinguish them from the collections of tens, hundreds, &c. The collections of tens are named ten, twenty, thirty, forty, fifty, sixty, seventy, eighty, ninety.(6). The intermediate numbers are expressed by joining the names of the units with the names of the tens. To express one ten and four units, we say fourteen, to express two tens and five units, we say twenty-five, and others in like manner.

The collections of ten tens, or hundreds, are expressed by placing before them the names of the units; as, one hundred, two hundred, and so on to nine hundred. The intermediate numbers are formed by joining to the hundreds the collections of tens and units. To express two hundred, four tens, and six units, we should

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