Charges on unpaid principal balance

Notwithstanding section 842, a licensee may contract for and receive charges on the unpaid principal balance at a single annual percentage rate, applied on the basis of the number of days actually elapsed, if the annual rate would produce a finance charge at the maturity of the contract not in excess of the finance charge resulting from the application of the graduated rates specified in section 838, when the loan is paid according to its terms, and charges are computed on the basis that a month is any period of 30 consecutive days, as provided in section 842, but if prepayment in full occurs on or before the third installment date, all charges must be recomputed as a percentage per month of the unpaid principal balance or portions thereof, based on the number of days actually elapsed.