Elementary arithmetic, with brief notices of its history... by Robert Potts.

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cent. per annum. 7. ~1 6s. 8d. per cent. 8. ~68 15s. 9. 15 months. 10. The
second is a little greater than the first. 11. 42 per cent. per annum. 12. 5 per
cent. per annum. 13. In 9 years.
V.
1. The sum is ~246 Is. 8d., the rate per cent. is 5`9-. 29. ~2501 13s. 39d.
3. The rate of interest is 7 dollars 30 cents per annum on 100 dollars. 4. The exact
interest in English money is 2s. 10]d. '1240475.
VI.
1. See Art. 6. 2. The discount is ~4 15s. 2"d., and the interest of this discount for one year at 5 per cent. will be found to be 4s. 91-d., which is the difference
between ~5, the interest, and ~4 15s. 2yd., the discount of ~100 for one year. 3.
The present worth is ~222 4s. 5-d., which, being deducted from ~250, leaves the
discount ~27 15s. 6-d. And the interest of ~222 4s. 5~-d. at 5 per cent. at 2- years
will be found equal to the discount of ~250. 4. ~673 4s. 11*d. 5. ~3 2s. 6d.
per cent. 7. ~733 19s. 3d. 8. ~100 amounts to ~122~ in five years, at 4~ per
cent. per annum. The sum required is ~816 6s. 7w1d. 9. ~1232 10s. 8`d. 10.
The interest due at the end of each half-year was ~62 10s. The question requires
the present worth of one-third of this sum, 3 months, one-third 2 months, and onethird 1 month, before the respective sums become due. 11. 625. 12. 18s. 61d.
13. ~9 3s. 4d. 14. See question 2 above, and Art. 6.
VII.
1. ~389 1ls. 4~d., amount when interest is payable yearly. ~390 9s. 11-d.,
amount when interest is payable half-yearly. 2. The rate ~12 10s. = of ~100.
The amount is ~1660 15s. 0]d. exactly. 3. ~129 6s. 4. The amount of ~100 for 3
yeais at 5 per cent. compound interest is ~115'7625. If ~60 be considered the
amount of which x pounds is the present worth, the sum will be found by a proportion to be ~51 16s. 71d.
5. If the third year's interest be found, the interest for 195 days of the third
year can be found by a proportion, and when this interest is added to the second
year's amount, the sum will be the amount at the end of 2 years 195 days, from
which, if the principal be subtracted, the remainder is the compound interest for
that time. This is only an approximation, not the true result. See Art. 5, p. 6, note.
6. Here the interest of ~410 is required for 10 periods, at the rate of 1l per cent.
per annum for each period.
7. The difference between the simple and compound interest of ~100 for 3 years
at 4 per cent. is ~1 19s. 8d. And the difference between the simple and compound
interest of the sum required is 19s. By a proportion the sum is found to be
~47 17s. 114d.
8. As the sum is not stated, let ~100 be taken, and the amount of ~100 in 2
years at compound interest is ~108 16s. The requirement is to find at what rate
simple interest ~100 will amount to ~108 16s. in 2 years.
9. Find the simple and compound interest of the given sum for 4 years, and
reduce the ratio of the interests to its simplest form.
10. Find the successive yearly amounts.
11. ~2027 Is. 61d.
12. The amount of ~100 for 5 years at 5 per cent. is ~123'812955; by a proportion may be found the present worth of ~100 5 years hence.
13. See the last question. 14. To the first year's amount add ~200, to make the
principal for the second year, and so on in succession for the given number of years.
15. The legacy accumulates for 6 years at compound interest.
16. See question 14.