17. A bookseller went to the city and bought a bill of books as follows: 12 readers at $1.25, 18 spellers at $.37, 10 geographies at $1.75, 8 primary geographies at $.621. In payment he gave a hundred dollar bill, how much should he receive back?

18. It took 25 yards of carpeting at $1.87 per yard for my sitting room, 50 yards of matting at $.65 per yard for my chambers, and 39 yards of oil-cloth at $ 1.25 per yard for my kitchen and halls; what was the amount of my bill? Ans. $128.12).

19. A ship carried to London from New Orleans 4500 bales of cotton, each bale weighing 475 pounds, at a freight of 23 cents per pound, and other merchandise upon which the freight was $8595; what was the whole amount of the ship's freight?

20. A drover bought stock as follows: 7 horses, at an average price of $225; 50 sheep at $ 3.50; and one pair of oxen for $200; what did the whole cost him?

21. A gentleman found that his household expenses for one month were as follows: provisions $175.50, groceries $150.50, house rent $83.33; what was the amount? What would be the amount for one year?

22. A farmer sold the produce of his farm as follows: 150 bushels of potatoes at $.55, 175 bushels of corn at $1.25, and 50 bushels of wheat at $4.50 per bushel; what was the amount he received?

23. A builder took a contract to build a house; he paid for brick and stone work, with materials, $3500; for carpenter work, with materials, $ 2575.50; for painting $675, and for other work $1550; he received $10,000; how much were his profits?

179. A COMPOUND NUMBER is composed of two or more denominations (Art. 92) which do not usually increase decimally from right to left; consequently, in adding the different denominations, we do not carry one for ten, but for the number it takes of the particular denomination added, to make a unit of the next higher denomination; thus, in adding Sterling or English money, we carry 1 for 4, 12, and 20, because 4qr. make 1d., 12d. make 1s., and 20s. make 1£.

Ex. 1. Add together 5£ 10s. 7d. 3qr., 6£ 18s. 11d. 2qr., 9£ 13s. 5d. 1qr., 17£ 16s. 9d. 3qr.

OPERATION.

£

S.

5

10

6 18

11

d. gr. 7 3 2

9 13

5

1

17

16

9

3

39 19 10 1

We first arrange the numbers as in the margin. Then add the right-hand column as in simple numbers, and find the amount to be 9qr. 2d. and 1qr. We write the 1qr. under

the column of farthings, and add the 2d. to the column of pence; the amount of which we find to be 34d. 2s. and 10d. We set the 10d. under the column of pence, and add the 2s. to the column of shillings, and find the amount to be 59s. 2£ and 19s. We write the 19s. in the column of shillings, and add the 2£ to the column of pounds; the amount of which we find to be 39£, and the whole amount

179. What is a compound number? How do they increase? What is said

of carrying?

180. The principle of this process is precisely the same as in addition of simple numbers. Hence,

To add compound numbers,

RULE. Write the numbers so that each denomination shall occupy a separate column, the lowest denomination at the right, and the others towards the left in the order of their values. Add the numbers in the lowest denomination, divide the amount by the number it takes of this denomination to make one of the next higher, set the remainder under the column, and carry the quotient to the next column. So proceed until all the columns are

NOTE. In writing, and also in adding the numbers of a SINGLE DENOMINATION, the rules of simple addition must be observed; thus in writing the pounds in Ex. 2, set units under units, tens under tens.

NOTE. A fraction occurring in the amount may sometimes be reduced to whole numbers of lower denominations; thus, in Ex. 9; we reduce the yd. to lower denominations 1ft. 6in., this we add to the ft. and in. in the example, and have 21rd. 2yd. 2ft. 7in.

10. A trader bought 4 hhd. of sugar: the first weighed. 10cwt. 3qr.. 171b.; the second 13cwt. 1qr. 191b.; the third 12cwt. 3qr. 181b.; and the fourth 11cwt. 3qr. 271b.; what did the whole weigh? Ans. 2t. 9cwt. 1qr. 61b.

11. I have my winter's wood in four piles; in one are 4c. 5 c. ft. 12 cu. ft.; in another 2 c. 7 c. ft. 9 cu. ft.; in another 1 c. 6 c. ft. 13 cu. ft. and in the fourth 3 c. 5 c. ft. 11 cu. ft.; how much wood have I in all?

Ans. 13 c. 1 c. ft. 13 cu. ft.

12. A vintner has wine in 3 casks; in the first, 68gal. 3qt. 1pt. 3gi.; in the second, 79gal. 2qt. 1pt. 1gi.; in the third, 94gal. 3qt. 1pt. 3gi.; how much has he in the three casks?

180. Rule for addition of compound numbers? Principle? Numbers of a single denomination, how written and added?

Proof?

SUBTRACTION.

181. The principle is like that of subtraction of simple numbers. Hence,

To subtract compound numbers,

RULE. 1. Write the less quantity under the greater, arranging the denominations as in addition.

2. Beginning at the right, take each denomination of the subtrahend from the number above it, and set the remainder beneath.

3. If any number of the subtrahend is greater than the number above it, add to the upper number as many as it takes of that denomination to make one of the next higher, and take the number in the subtrahend from the SUM; set down the remainder, and considering the number in the next denomination in the minuend ONE LESS, or that in the subtrahend ONE GREATER, proceed as before.

PROOF. As in subtraction of simple numbers.

Ex. 1. From 12£. 9s. 6d. 3qr. take 8£. 7s. 9d. 2qr.

=

and reduce it to pence, which with the 6d. in the example = 18d. We now say 9d. from 18d. leave 9d. which we write in its proper place, under the pence in the example. Now, as one

181. Rule for subtraction of compound numbers? Principle? Proof?