A licensee may charge and collect interest in respect of a loan at such daily, weekly, monthly, annual or other periodic percentage rate or rates as the agreement governing the loan provides or as established in the manner provided in such agreement and may calculate such interest by way of simple interest or such other method as the agreement governing the loan provides. If the interest is precomputed it may be calculated on the assumption that all scheduled payments will be made when due. For purposes hereof, a year may but need not be a calendar year and may be such period of from 360 to 366 days, including or disregarding leap year, as the licensee may determine.