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II. To find the interest of any number of cents for any number of days less than a month, at 6 per cent.


Multiply the cents by the number of days, divide the product by 6, and point off two figures to the right, and all the figures at the leit hand of the dash, will be the interest in mills, nearly.


Required the interest of 85 dollars, for 20 days. cts.

mills. $5 =8500X20-6=283,33

Ans. 283 which is

28cts. 3mills. 2. What is the interest of 73 dollars 41 cents, or 7341 cents, for 27 days, at 6 per cent. ?

Añs. 330mills, or 33cts.

III. When the principal is given in pounds, shillings, &c.

New-England currency, to find the interest for any number of days, less than a month, in Federal Money.

RULE. Multiply the shillings in the principal by the number of days, and divide the product by 36, the quotient will be the interest in mills, for the given time, nearly, omitting fractions


Required the interest in Federal Moneyy of 271. 15s or 27 days, at 6 per cent.

£. Ans. 27 15=555X27:-36x416mills. 41 cts. Om


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V. When the principal is given in Federal Money, and you want the interest in shillings, pence, &c. New-Eng. land currency,

for any number of days less than a month

RULE. Multiply the principal, in cents, by the number of days, and point off five figures to the right hand of the product, which will give the interest for the given time, in shillings and decimals of a shilling, very nearly,


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A note for 65 dollars, 31 cents, has been on interest 25 days; how much is the interest thereof, in New-England currency?

$ cts.

Ans. 65,3136531X25=1,6327531 7 2 REMARKS.-In the above, and likewise in the preceding practical Rules, (page 127) the interest is confined at 6 per cent. which admits of a variety of short methods of casting; and when the rate of interest is 7 per cent. as established in New York, &c. you may first cast the interest at 6 per cent. and add tbereto one sixth of itself, and the sum will be the interest at 7 per cent. which perhaps, many times, will be found more convenient than the general rule of casting interest.

Required the interest of 75l. for 5 months at 7 per cent.

7,5 for 1 month.

£. s. d.
37,5=1 17 6 for 5 months at 6 per cent.

6 3

Ans. £2 3 9 for ditto at 7 per cent.


RULE. Diminish the interest of the given sum for the time by its own interest, and this gives the Rebate very nearly.

EXAMPLES. 1. What is the rebate of 50 dollars for six months, at o

per cent. ?

£. s.

$ cts The interest of 50 dollars for 6 month, is

1 50 And, the interest of 1 dol. 50 cts. for 6 months, is

Ans. Rebate, $1 46 2. What is the rebate of 1501. for 7 months, at 5 per cent. ?

d. Interest of 1501. for 7 months, is 4 76 Interest of 4l. 7s. 6d. for 7 months, is

2 61

Ans. £4 4 11} nearly. By the above Rule, those who use interest tables in their counting-houses, have only to deduct the interest, of the interest, and the remainder is the discount. A concise Rule to reduce the currencies of the different

States, where a dollar is an even number of shillings, to Federal Money.

RULE I. Bring the given sum into a decimal expression by inspection, (as in Problem I. page 87) then divide the whole by ,3 in New-England and by ,4 in New-York currency, and the quotient will be dollars, cents, &c.


1. Reduce 541. 8s. 31d. New-England currency, to Federal Money.

,3)54,415 decimally expressed.

Ans. $181,38 cts. 2. Reduce 7s. in d. New-England currency, to Federal Money. 73. 11d.-£0,399 then, ,3),399

Ans. $1,33 3. Reduce 5131. 16s. 10d. New-York, &c. currency, to Federal Money.

94)513,842 decimale Ans. $1284,601

4. Reduce 19s. 5 d. New-York, &c. currency, to Federal Money.

,40,974 decimal of 19s. 5 d.

$2,434 Ans. 5. Reduce 641. New-England currency, to Federal Money.

,364000 decimal expression.

$213,331 Ans. Note. By the foregoing rule you may carry on the decimal to any degree of exactness; but in ordinary practice, the following Contraction may be useful.

RULE II. To the shillings contained in the given sum, annex 8 times the given pence, increasing the product by 2 ; then divide the whole by the number of shillings contained in a dollar, and the quotient will be cents.


1. Reduce 45s. 6d. New-England currency, to Federal Money.


50 to be annexed. 6)45,50 or 6)4550

$ cts. $7,583 wins. 758 cents. =7,58. 2. Reduce 21. 10s. 9d. New-York, &c. currency,to Federal Money,

9x8+2=74 to be annexed. Then 8)5074

Or thus, 8)50,74

cts. Ans. 634 cents.6 34

$6,34 Ans. N. B. When there are no pence in the given sum, you must annex two ciphers to the shillings; then divide as before, &c.

3. Reduce 31. 5s. New-England currency, to Federal Money.

31. 55.=65s. Then 6)6500

Ans. 1083 cents


SOLIDS. SECTION 1. OF SUPERFICIES. The superficies or area of any plane surface, is composed or made up of squares, either greater or less, according to the different measures by which the dimensie ; of the figure are taken or measured :—and because 12 ...ches in length make l-foot of long measure, therefore, 12X12=144, the square inches in a superficial foot, &c.

ART. I. To find the area of a square having equal sides.

RULE Multiply the side of the square into itself and the product will be the area, or content.

EXAMPLES. 1. How many square feet of boards are contained in the floor of a room which is 20 feet square ?

20x20=400 feet, the Answer. 2. Suppose a square lot of land measures 26 rods on each side, how many acres doth it contain ?

NOTE.-160 square rods make an acre.
Therefore, 26X26=676 sq. rods, and 676-160=4a.

36r. the Answer. ART. 2. To measure a parallelogram, or long square.

RULE. Multiply the length by the breadth, and the product will be the area, or superficial content.


1. A certain garden, in form of a long square, is 96 ft. long, and 54 wide ; how many square feet of ground are contained in it ? Ans. 96X54=5184 square feet.

2. A lot of land, in form of a long square, is 120 rods in length, and 60 rods wide ; how many acres are in it ?

120X60=7200 sq. rods, then 12.00=45 acres. Ans.

3. If a board or plank be 21 feet long, and 18 inches broad; how many square feet are contained in it ?

18 inches 1,5 feet, then, 21X1,531,5. Ans.

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