2.—(1) Where any amount falls to be taken into account for the purposes of these Regulations, it shall be calculated or estimated as a weekly amount and, except where the context otherwise requires, any reference to such an amount shall be construed accordingly.
(2) Subject to regulation 13(2), where any calculation made under these Regulations results in a fraction of a penny that fraction shall be treated as a penny if it is either one half or exceeds one half, otherwise it shall be disregarded.
(3) A child support officer shall calculate the amounts to be taken into account for the purposes of these Regulations by reference, as the case may be, to the dates, weeks, months or other periods specified herein provided that if he becomes aware of a material change of circumstances occurring after such date, week, month or other period but before the effective date, he shall take that change of circumstances into account.