Illustration of the foregoing table.--To find the number of days from August 15th, 1829, to February 15th, 1830, I find August in the left hand column, and Feb. at the top of the table; and against the former month, and under the latter, I find 184, the number of days required. In like manner the number of days from any day of any given month to the same day of any other month may be found.

If the given days of the months be different, the difference must be added to, or subtracted from the tabular number, as the case shall require. Thus, to find the number of days from March 4th, to July 20th, (of the same year,) I find, by the table, that the number of days from the 4th of March to the 4th of July is 122; to which I add 16, (the difference between 4 and 20,) and the sum is 138 days, the time required. Again, to find the number of days from May 21st to Dec. 11th, I look in the table, and find that from May 21st to Dec. 21st there are 214 days; from which number I subtract 10, (the difference between 21 and 11,) and the remainder is 204, the number of days required.

In leap years, if the last day of February be included in the given time, the tabular number must be increased 1. Thus, from the 1st day of Feb. to the 1st day of May, in leap year, there are 89+1=90 days.

The following method of computing interest for days is very accurate, and when the principal is Federal money, and the rate per cent. is an aliquot part of 36, it is very convenient.

RULE II.-For Federal Money.

1. Multiply together the given principal and the number of days, and point off in the product three more decimal places than usual. Subtract from this product one-seventieth part of itself, and the remainder will be the interest at 36 per cent.

2. When the given rate per cent. is an aliquot part of 36, the like proportional part of the interest at 36 per cent. will be the interest required. When the rate per cent. is not an aliquot part of 36; multiply the interest at 36 per cent. by the given rate; divide the product by 36, (or divide

twice by 6,) and the quotient will be the interest required.* Note 1.-To deduct of the product of the principal and days, divide the said product by 7, set the quotient one place farther to the right hand than usual in short division, and subtract it from the dividend.

Note 2.-The 2d Note under Rule II. Prob. I. is also applicable to this Rule.

EXAMPLES.

1. What is the interest of 84D. 28c. for 40 days, at 6 per cent. per annum?

$84.28

40

7)3.37120
.048

36÷6=6)3.323

Ans. $.553+

Here, because the rate per cent. is of 36, I take of the interest at 36 per cent., for the interest required. In performing the operation I reject all the figures beyond the place of mills. Fractional parts of a mill may always be rejected in computing interest by this rule.

2. What is the interest of $100 for 147 days, at 6 per cent.? Ans. $2.415 3. Required the interest of $78 for 64 days, at 4 per cent. Ans. 54c. 6m.+ 4. Required the interest of 675D. 50c. from the 4th of October, 1829, till the 1st of February, 1830, at 7 per cent. Ans. $15.5365 April 1st till June Ans. $1.642+

5. Required the interest of $150 from 20th, of the same year, at 5 per cent.

Note 3.-When the rate per cent. is not an aliquot part of 36, it will sometimes be convenient to first compute the interest at some other rate, which is an aliquot part of 36, and then increase or diminish the interest thus found, by some part or parts of itself which will give the true interest required. Thus, if the interest at 6 per cent. be increased by of itself, the sum will be the interest at 7 per cent.; or, if the interest at 6 per cent. be diminished by of itself, the

* The interest of $1, at 36 per cent. per annum, (reckoning 365 days to the year,) is very nearly of a mill per lay; whence the reason of this rule is obvious.

remainder will be the interest at 5 per cent.: Also, of the interest at 9 per cent. is the interest at 4 per cent., &c. It will be well for the learner to solve questions 4th and 5th in this way.

Note 4.-When the rate is 7 per cent. the interest may be computed as follows: From twice the given principal subtract part of the said principal; multiply the remainder by the number of days; point off in the product four more decimal places than usual in multiplying decimals, and you will have the interest required.*

6. What is the interest of $25.86 for 80 days, at 7 per annum?

cent. per

12)25.86D.

2

51.72

-2.155

49.565

80

Ans. $.3965200

7. Find, by the method laid down in the last Note, the interest of $72, for 172 days, at 7 per cent. Ans. $2.3736

When you wish to close an account current, and intend to charge interest on every particular entry, the shortest method of computing the interest, is the following:

1. Find the number of days from the date of the first charge to the close of the account, or time of settlement. Proceed in the same manner with all the accounts, both on the Dr. and Cr. sides.

2. Multiply each sum on the Dr. side by its correspond

*This is a very easy and accurate method of computing interest at 7 per cent. The method is a contraction of the 2d general rule for computing interest for days.

An account current contains a statement of the mercantile transac tions of one person with another, when immediate payments are not made.

ent number of days,and add all these products into one sum total. In like manner, multiply each sum on the Cr. side by its correspondent number of days, and find the sum of the products.

3. Find the difference between the two sums of products, (by subtracting the less from the greater,) which difference multiply by the rate of interest per cent.; divide the product by 36500, and the quotient will be the interest required. The interest, thus found, must be added to the amount of the debts when the sum of the products on the Dr. side exceeds the sum of the products on the Cr. side; but when the latter sum exceeds the former, then the interest belongs on the Cr. side.

Note. When goods are sold on a stipulated credit, i. e, for three, six, or nine months, or whatever time may be agreed on; that time must be taken off, in computing interest on the value of such goods, which is readily done by beginning to count the time of each charge so much after its date.

EXAMPLES.

Ex. 1. James Smith, Baltimore, in Account Current with David Wanzer, New-York.

To close this account on the 10th day of Dec. 1829; who is indebted, and how much, allowing interest at the rate of 7 per cent. per annum?

James Hicks, 250

Then, to 916.50 the amount of the debts,
add 11.21 the interest due.

From this, 927.71

subtract 765.00 the amount of Cr.

Ans. $162.71 Due to D. Wanzer.

Ex. 2. J. Fox, New-Orleans, in Account Current with A. Davis, New-York.

How much remained due on this account on the 26th of June, 1830; computing interest at 6 per cent. per annum? Ans. $187.067+

PROBLEM IV.

To compute interest on Notes, Bonds, &c., having partial payments endorsed.

There has hitherto been much diversity of opinion relative to the computation of lawful interest on notes, bonds, &c., on which partial payments have been made; and several different rules have been adopted by the Courts in the