(a) In computing any period of time under this part or in an order issued under it, the time begins with the day following the act, event, or default, and includes the last day of the period, unless it is a Saturday, Sunday, or legal holiday that is observed by the Federal government, in which event it includes the next business day.

(b) When the period of time allowed is less than seven days, intermediate Saturdays, Sundays, and legal holidays that are observed by the Federal government are excluded from the computation.

(c) Where a document has been served or issued by placing it in the mail, an additional five days will be added to the time permitted for any response.