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FEDERAL MONEY. II. To find the interest of any number of cents for any number of days less than a month, at 6 per cent.
RULE. 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 left hand of the dash, will be the interest in mills, nearly.
Required the interest of 85 dollars, for 20 days. $ cts.
mills. 85=8500 x 20-63283,33
Ans. 283 which is
28 cts. 3 mills. 2. What is the interest of 73 dollars 41 cents, or 7341 cents, for 27 days, at 6 per cent. ?
Ans. 330 mills, or 33 cts.
HI. 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 Money, of 271. 158. far 27 days, at 6 per cent.
£ s. Ans, 27 15-555x27+36-416 mills.-41cts. 6m
W. When the principai is given in Federal Money, and you want the interest in shillings, pence, &c. NewEngland arrency, for any number of days less than a
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 skil linys and decimals of a shilling, very nearly.
A note for 65 dollars, 31 cents, has been on interest 25 days; how much is the interest thereof, in New-England currency?
Ans. 65,31=6531x25=1,63275 3172 REMARKS.-In the above, and likewise in the preced. ing practical Rules, (page 127) the interest is confined at six 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 in. terest at 6 per cent. and add thereto one sixth of itself, and the sum will be the interest at 7 per cent. which per haps, many times, will be found more convenient than the general rule of casting interest.
EXAMPLE. Required the interest of 75l. för 5 months at 7 per sent.
7,5 for 1 month
f. s. d.
= 6 3
Ans. £2 3 9 for ditto at 7 per cent.
A SHORT METHOD FOR FINDING THE REBATE OF AXY GIVEN SUM, FOR MONTHS AND DAYS. 1
RULE. Diminish the interest of the given sum for the time by ts own interest, and this gives the Rebate very nearly.
1. What is the rebate of 50 dollars for six months, at per cent. ?
$ cta The interest of 50 dollars for 6 months, is 1 50 And, the interest of i dol. 50 cts. for 6 months, is
Ans. Rebate., SI 46 2. What is the rebate of 1501. for 7 months, at 5 per cent. ?
aterest of 1501. for 7 months, is 4 7 6 nterest of 41. 78. Gd. for 7 months, is 2 64
Ans. 64 4 115 nearlyBy the above Rule, those who use interest tables in their counting-houses, have only to derluct the interest of the interest, and the remainder is the discvant.
A carcise 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 l. page 87, then divide the whole by ,3 16 New England and by 4 in New-York currency, and the quotient will be dollars, cents, &c.
1. Reduce 541. 85. 31d. New-England currency, to Federal Moner.
93)54,413 decimally expressed.
ins. $181,38 ets. 2. Reduce 78. 118d. New-England currency, to vedo. ni Monev.
78 1140.-€0,899 then, ,s),599
Ans. $1,33 3. Reduce 5156. 166. 10d. New-York, &c. currency, to Federal Money.
4. Reduce 195. 5jd. New-York, dus currency, to federal Money.
,4)0,974 decimal of 199 5fd.
82,434 Ans. 5. Reduce 641. New-England currency, te Federal Money.
,3)64000 decimal expression.
8213,334 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 livide the whole by the number of shillings contained in a dollar, and the quotient will be cents.
1. Reduce 45s.6d. Ncw-England currency, to Pede. ral Money.
6x8+2 =50 to he annexed,
$ cts. 87,58% Ans. 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
86,34 Ans N: B. 'When there are no pence in the given sum, you Huust anpex two cyphers to the shillings; then divile as before, &c.
3. Reduce. Sl. 58. New-England currency, to Yodern money.
.Sh. 50.-2656. Then 6)6500
7SOME USEFUL RULES, FOR FINDING THE CONTENTS OF SUPERFICIES AND
SECTION I. OF SUPERFICIES. The superficies or area of any plane surface, is composed or inade up of squares, either greater or less, according to the different measures by which the dimensiuns of the figure are taken or measured :-and because 12 inches in length make 1 foot of long measure, there fore, 12x12=144, the square inches in a superficial foot,
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.
1. How many square feet of boards are contained in the door 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 ?
NoȚE.- 160 square rods make an acre.
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.
EXAMPLES 1. A certain garden, in forin of a long square, is 96 ft. ong, and 54 wide; how many square feet of ground are contained in it! Ans. 96x54=5144 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 sqr. rods, then Yo=45 acres. Ans. 3. If a board or plank be 21 feet long, and 18 inches taroad; how many square feet are contained in it ?
. '18 inches21,5 feet, then 21x1,5=31,5 Ans.