In the formula in subparagraph a of the first paragraph,(a) A is the aggregate of all amounts each of which is the amount computed under section 818R73 in respect of a full month in the year, or in respect of the part of the month that ends after the last full month in the year, if that part is greater than 15 days;
(b) B is the amount described in section 818R72; and
(c) C is the number of full months in the year plus 1, if the year ends more than 15 days after the end of the last full month in the year.