Divide the principal by 100; then divide that quotient by the aliquot parts of a pound arising from the rate per

cent.

ILLUSTRATION.

5s. = one fourth of a pound; 4s. = one fifth of a pound; 6s. = one fifth of a pound and one fifth of that fifth; 6s. 8d. = one third of a pound; 2s. 6d. = one eighth of a pound,

What is the brokage of 350 dollars at the rate of 60

LESSON 14.

What is the brokage of 455.25 dollars, at the rate of 70

“As 365 days are to the interest of the given sum for one year;

So is the time proposed, to the interest required."

LESSON 15.

What is the interest of 5075 cents for 90 days, at 7 per

2772

2555

.2175

1825

.3500

3285

.215+

RULE FOR PROOF.

Multiply the principal in cents by the rate per cent., and that product by the number of days for a dividend. Multiply 365 by 100 for a divisor; the quotient will be the answer in cents.

1 day equals of a month.||6 months equal of a year.

2358*

10

15

4

3

2

13

LESSON 16.

What is the interest of a note given on the first day of January, 1815, for 34 dollars and 50 cents, payable on the 6th of February, 1816, with interest at 7 per cent. per an

In small business this method will be sufficiently exact, but in large sums it is advisable to calculate by the preceding rules, because 30 days fall short of of a year.

COMPOUND INTEREST.

Find the interest of the given sum for 1 year, add that interest to the principal and call it the amount. Take this amount for the principal of the second year: Find the amount for the second year and make it the principal of the third year, &c. &c.

NOTE.-Subtract the given sum from the last amount, the remainder will be compound interest.

LESSON 17.

What is the compound interest of 500 dollars for 4 years, at 7 per cent. per annum? Ans. 155 dol. 39 cents. Principal for the first year, 50000 cents.

Rate per cent.

7

3500100

[Continued.

dollars, 39 cents, 8 tenths and 5 ten thousandths of a

cent.

DECIMAL INTEREST.

Make a common multiplier for the rate per cent. thus: If 100 cents in 1 year give 7 cents interest, what will 1 cent give in the same time?

100: 7:1

Here appears to be 7 hundredths of a cent for the inte rest of 1 cent 1 year: This .07 we will call a common multiplier, by which any number of cents may be multiplied, and the product will be their interest at 7 per cent. for 1

year.

43