The Canadian Interest Rule.
Too Long; Didn't Read
This rule of computing interest appears in some Canadian text-books, and, though simply a modification of other rules, is worthy of notice. To find the interest on $724 for 5 1/2 months at 6 per cent., all you have to do is to divide by 4 and multiply by 11. The rule is to divide the principal by 4, and to multiply the quotient by one-third of the product of the rate by the time in months. Six times 5 1/2 = 33, and one-third of 33 is 11. If the time be expressed in years, multiply one-fifth of the principal by one-half the product of the rate by the number of years, and remove the decimal point one place to the left.