places to the left, § 170, leaving four places for decimals to the right hand. If the principal had contained mills, there would have been five places of decimals in the answer. § 187. Hence we have the following RULE. I. When the principal contains dollars only, multiply by the rate of interest, and point off two places from the right hand for cents: the places on the left will express the dollars. II. When the principal contains dollars and cents, multiply as before, and strike off four places from the right hand for cents and mills. III. When the principal contains dollars, cents, and mills, multiply as before and strike off in the product five places from the right hand: the places to the left will be dollars. Ex. 4. What is the interest on $375, 27 cts. 3 mills for two years, at 7 per cent. perann. ? $375,27,3 7 $26,26,9,11 Interest for one year. 2 $52,53,8,22 Ans. $52,53+. 5. What is the interest on $211,26 for one year at 4 per cent.? $211,26 41 per cent. 84504 10563 per cent. 9,50,67 Ans. 6. What is the interest on $1576,91 for 3 years at 7 per cent.? Ans. $331,15+. 7. What is the interest on $957,08 for 6 31 per cent. ? Ans. $200,98+. CASE II. § 188. To find the interest at 6 per cent. per annum for any number of months. At six per cent. per annum, each month produces per cent. on the principal; and every two months produces one per cent. on the principal. Therefore, to find the interest for months we have the following RULE. Multiply the principal by half the number of months, and remove the separating point in the product two places farther to the left hand. 6 1. What is the interest of $327 for 8 months at per cent. per annum ? $327 4 half the number of months. Ans. $13,08 2. What is the interest of $327,47 for 9 months at 6 per cent. per annum? $327,47 find the interest at 6 per cent. per annumber of days. Since in computing interest the month is always reckoned at 30 days, 60 days, which make 2 months, will give an interest of one per cent. on the principal. Now, if the interest at one per cent. (which is the principal with the separating point removed two places to the left,) be divided by 60, the quotient will be the interest for 1 day, and this quotient multiplied by the number of days will give the interest required. To divide by 60 we remove the separating point one place farther to the left, and then divide by 6. Hence we have the following RULE. I. Remove the separating point in the principal three places to the left, then divide by 6 and the quotiet will be the interest for 1 day. II. Multiply the interest by the number of days, and the product will be the answer sought. Ex. 1. What is the interest on $327,30 for 25 days? 6),32730 2. What is the interest on $27,25 for 19 days? 3. What is the interest of $575,72 for 29 days? Ans. $2,78+. 4. What is the interest of $195,19 for 7 days? Ans. $0,22+. CASE IV. 190. To find the interest at 6 per cent. per annum for years, months, and days. RULE. Find the interest for the years by Case I., for the months by Case II., and for the days by Case III.; then add the several results together, and their sum will be the answer sought. Ex. 1. What is the interest on $1597,27 at 6 per cent. for 3 years 9 months and 11 days? 2. What is the interest of $11759,10 at 6 per cent. for 9 years 11 months and 16 days? Ans. $7028,02+. 3. What is the interest on $9787 for 12 years and 1 day? Ans. $7048,27+. 4. What is the interest of $87601,29 for 1 year Ans. $5708,68+. 1 month and 1 day? 5. What is the interest of $806,90, for 1 year and 10 months at 6 per cent. per annum? Ans. $88,75+. 6. What is the interest of $450,75 for 4 years and 7 months, at 6 per cent. per annum ? Ans. $123,95+. years 2 7. What is the interest of $443,50 for 7 months and 12 days, at 6 per cent. per annum? Ans. $191,59+. 8. What will be the total amount of $649,22 after 10 years and 10 months, at an interest of 6 CASE V. per cent? Ans. $1071,21+. 191. When there are months and days, and the rate of interest is greater or less than 6 RULE. per cent. Find the interest as at 6 per cent. Then add to it or subtract from it such a part of the interest so found as the given rate exceeds or falls short of six per cent. per annum. Ex. 1. What is the interest of $119,50 at 7 per cent. per annum, for 3 years and 4 months? 119,50 2 half the months $2,39,00 int. for 4 mo. 119,50 6 7,17,00 3 21,51,00 int. for 3 yr. 2,39,00 int. for 4 mo. 3,98,33+ Total interest at 6 per cent. $23,90,00 Add one sixth Total interest at 7 per ct. $27,88,33+ |