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IV. When the principal is given in pounds, shillings, &c New-England currency, at 6 per cent. to find how much the monthly interest will be in federal money.

RULE.-Multiply the pounds, &c. by 5, and divide that product by 3, the quotient will be the interest for one month, in cents, and deci. mals of a cent, &c.

EXAMPLES.

1. A note for £411 New-England currency bas been on interest one month; how much is the interest thereof in fe. deral money?

£. 411

5

3)2055

Ans. 685 cts.=$6, 85 cts. 2. Required the interest of 391. 18s. N. E. currency, for 7 months ?

£
39,9 decimal value.

5

3)199,5

Interest for 1 mo. 66,5 cents.

7

Ditto for 7 mo. 465,5 cts.=$4, 65 cts. 5 m. Ans.

V. When the principal is given in New England and Vir ginia currency, at 6 per cent. to find the interest for a year, in dollars, cents, and mills, by inspection.

Rule. Since the interest of a year will be just so many cents as the given principal contains shillings, therefore, write down the shil. kings and call them cents, and the pence in the principal made less by 1 if they exceed 3, or by 2 when they exceed 9, will be the mills, very Dearly.

EXAMPLES.

.chi

1. What is the interest of 21. 5s. for a year, at 6 per ct. ?

£2 5s=458. Interest 45 cts. the Answer. 2. Required the interest of 1001. for a year, at 6 per ct. 3

£100=2000s. Interest 2000 cts.=$20 Ans. 3. Of 27s. 6d. for a year?

Ans. 27s. is 27 cts. and 6d. is 5 m. 4. Required the interest of 5l. 10s. 11d. for a year ?

£5 10s.=110s. Interest 110 cts.=$1, 10 cts. Om. 11 pence.-2

9 2 per rule leaves 9=

Ans. $1, 10

20

VI. To compute the interest on any note or obligation, when there are payments in part, or endorsements.

Rule.-1. Find the amount of the whole principal for the whole time.

2. Cast the interest on the several payments, from the time they were paid, to the time of settlement, and find their amount; and lastly, deduct the amount of the several payments from the amount of tho principal.

EXAMPLES. Suppose a bond or note dated April 17, 1793, was given for 675 dollars, interest at 6 per cent. and there were payments endorsed upon it as follows, viz.

First payment, 148 dollars, May 7, 1794.
Second payment, 341 dols. August 17, 1796.
Third payment, 99 dols. Jan. 2, 1798. I demand how
much remains due on said note, the 17th June, 1798 ?

* cts.
148, 00 first payment, May 7, 1794.
36, 50 interest up to June 17, 1798.=4 l}

Yr. mo.

184, 50 amount

341, 00 second payment, Aug. 17, 1796. Yr. mo.
37, 51 interest to June 17, 1798. =1

10
378, 51 amount.

Carried over.]

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cts.
99, 00 third payment, January 2, 1798.
2, 72 interest to June 17, 1798.=54 mb.

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664, 73 total amount of payments.
675, 00 note, dated April 17, 1793.

Yr. mo
209, 25 interest to June 17, 1798. -5 2
884, 25 amount of the note.

664, 73 amount of payments. $219, 52 remains due on the note, June 17, 1798. 2. On the 16th January, 1795, I lent James Paywell 500 dollars, on interest at 6 per cent. which I received back in the following partial payments, as under, viz. 1st of April, 1796

$ 50 16th of July, 1797

400 1st of Sept. 1798

60 How stands the balance between us, on the 16th Novem. ber, 1800 ?

Ans. due to me, $63, 18 cts. 3. A PROMISSORY NOTE, viz. £62 10s.

New-London, April 4, 1797. On demand, I promise to pay Timothy Careful, sixty-two pounds, ten shillings, and interest at 6 per cent. per annum, till paid; value received. JOHN STANBY,

PETER PAYWELL. RICHARD TESTIS.

Endorsements.
1st. Received in part of the above note,
September 4, 1799,

50 0
And payment June 4, 1800,

12 10 How much remains due on said note, the 4th day of De. Canber, 1800.

£. s. d. Ans. 9 12 6

£. 8.

Note.-The preceding Rule, by custom, is rendered so popular, and so much practised and esteemed by many on account of its being simple and concise, that I have given it a place: it may answer for short periods of time, but in a long course of years, it will be found to be very errones ous.

Although this method seems at first view to be upon the ground of simple interest, yet upon a little attention the following objection will be found most clearly to lie against it, viz. that the interest will, in a course of years, completely expunge, or as it may be said, eat up the debt. For an explanation of this, take the following

EXAMPLE.

A lends B 100 dollars, at 6 per cent. interest, and takeš his note of hand; B does no more than pay A at every St year's end 6 dollars, (which is then justly due to B for the d use of his money) and has it endorsed on his note. At the

end of 10 years B takes up his note, and the sum he has to pay is reckoned thus: The principal 100 dollars, on interest 10 years amounts to 160 dollars ; there are nine endorsements of 6 dollars each, upon which the debtor claims interest; one for nine years, the second for 8 years, the third for 7 years, and so down to the time of settlement; the whole amount of the several endorsements and their interest, (as any one can see by casting it) is $70, 20 cts. this subtracted from 160 dols. the amount of the debt, leaves in favour of the creditor, $89, 40 cts. or $10, 20 cts. less than the original principal, of which he has not received a cent, but only its annual interest.

If the same note should lie 20 years in the same way, B would owe but 37 dols. 60 cts, without paying the least fraction of the 100 dollars borrowed.

Extend it to 28 years, and A the creditor would fall in Di

debt to B, without receiving a cent of the 100 dols. which he lent him. See a better Rule in Simple Interest by decimals.

page

175:

U

COMPOUND INTEREST,

IS when the interest is added to the principal, at the end of the year, and on that amont the interest cast for another year, and added again, and so on : this is called interest upon interest.

RULE. --Find the interest for a year, and add it to the principal, which call the amount for the first year; find the interest of this amount, which add as before, for the amount of the second, and so on for any number of years required. Subtract the original principal from the last amount, and the remainder will be the Compound Interest for the whole time.

EXAMPLES.

1. Required the amount of 100 dollars for 3 years at 6 per centper annum, compound interest?

$ cts.

$ cts, 1st Principal 100,00 Amount 106,00 for 1 year. 3d Principal 106,00 Amount 112,36 for 2 years. 3d Principal 112,36 Amount 119,1016 for 3 yrs. Ans.

2. What is the amount of 425 dollars, for 4 years, at 3 per cent. per annum, compound interest?

Ans. $516, 59 cts. 3. What will 4001. amount to, in four years, at 6 per cent. per annum, compound interest ?

Ans. £504 19s. 9 d. 4. What is the compound interest of 1501. 10s. for 3 years, at 6 per cent. per annum? Ans. £28 14s. 11 d. +

5. What is the compound interest of 500 dollars for 4 years, at 6 per cent, per annum ? Ans. $131,238+

6. What will 1000 dollars amount to in 4 years, at 7 per cent. per annum, compound interest?

Ans. $1310, 79 cts. 6 m. + 7. What is the amount of 750 dollars for 4 years, at 6 per cent. per annum, compound interest?

Ans. $946, 85 cts. 7,72 m. 8. What is the compound interest of 876 dols. 90 cents for 8; years, at 6 per cent. per annum ?

Aps.. $198, 83 cts-fo

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