Chapter 5
Calculating Interest To find the interest on any sum, at any rate percent, and for any length of time, first multiply the principal by the rate percent expressed in hundredths. This will give the interest for one year. Second, find the number of days remaining by consulting the calendar, and multiply the
principal by as many hundredths as there are days. And for 3%, divide the product by 120. For 4%, divide by 90. For 5%, divide by 72. For 6%, divide by 60.
For 7%, divide by 52. For 8%, divide by 45. For 9%, divide by 40. For 10%, divide by 36. And for 12%, divide by 30.
This will give the interest for the days. Third, add the two items of interest and the sum will be the entire interest. To find the number of days from any day of any one month to the same day of any other month, please consult the following table. Starting from the month of January, there are 365 days till the next January, 31 days
till February, 59 days till March, 90 days till April, 120 days till May, 151 days till June, 181 days till July, 212 days till August, 243 days till September, 273 days till October, 304 days till November, and 334 days till December. Starting from the month of February, there are 334 days till January, 365 till February, 28 till March, 59 till April, 89 till May, 120 till June, 150 till July, 181 till August,
212 till September, 242 till October, 273 till November, and 303 till December. Starting from the month of March, there are 306 days till January, 337 days till February, 265 days till March, 31 days till April, 61 days till May, 92 days till June, 122 days till July, 153 days till August, 184 days till September, 214 days till October, 245 days till November, and 275 days till December. Starting from the month of April, there are 275 days till January,
306 days till February, 334 days till March, 365 till April, 30 till May, 61 till June, 91 till July, 122 till August, 153 till September, 183 till October, 214 till November, and 244 till December. Starting from the month of May, there are 243 days till January, till January, 276 till February, 304 till March, 335 till April, 365 till May, 31 till June, 61 till July, 92 till August, 123 till September, 153 till October, 184 till November, and 214 till
December. Starting from the month of June, there are 214 days till January, 245 days till February, 273 days till March, 304 days till April, 334 days till May, 365 days till June, 30 days till July, 61 days till August, 92 days till September, 122 days till October, 153 days till November, and 183 days till December. Starting from the month of July, there are 184 days till January, 215 days till February, 243 till March, 274 till April, 304 till May, 335 till June,
365 till July, 31 till August, 62 till September, 92 till October, 123 till November, and 153 till December. Starting from the month of August, there are 153 days till January, 184 days till February, 212 days till March, 243 days till April, 273 days till May, 304 days till June, 334 days till July, 365 days till August,
31 days till September, 61 days till October, 92 days till November, and 122 days till December. Starting from September, there are 122 days till January, 153 days till February, 181 days till March, 212 days till April, 242 days till May, 273 days till June, 303 days till July, 334 days till August, 365 days till September, 30 days till October, 61 days till November, and 91 days till December.
Starting from the month of October, there are 92 days till January, 123 till February, 151 till March, 182 till April, 212 till May, 243 till June, 273 till July, 304 till August, 335 till September, 365 till October, 31 till November, and 61 till December. Starting from the month of November, there are 61 days till January, 92 days till February, 120 days till March, 151 days till April, 181 days till May, 212 days till June,
242 days till July, 273 days till August, 304 days till September, 334 days till October, 365 days till November, and 30 days till December. Starting from the month of December, there are 31 days till January, 62 days till February, 90 days till March, 121 days till April, 151 days till May, 182 days till June, 212 days till July, 243 days till August, 274 days till September, 304 days till October, 335 days till November,
and 365 days till December. Nota bene. In leap year, if the last day of February comes between, add one day to the number in the table.
