Accurate Interest.
Interest is the sum charged for the use of money. It is really the use of money or the benefit derived from its use. The principal is the sum for the use of which interest is paid. The rate of interest is the per cent. of the principal charged for its use for one year. Simple interest is the interest on the principal only, for the full time; compound interest is interest on the principal for the full time, and interest on each interest payment after it becomes due.
To find the accurate interest on any sum of money at a given rate for one year, multiply the sum by the rate and divide by 100.
To find the accurate interest on any sum of money at a given rate for any given number of days, multiply the interest for one year by the number of days and divide the product by 365.