Rule 20. Computation and extension of time.

(a) Computation of time. When the computation of any period of time prescribed or allowed by these rules is by order of court or by an applicable statute, the day of the act, event, or default after which the designated period of time begins to run may not be included. The last day of the period so computed shall be included unless it is a Saturday, Sunday, or legal holiday. When the period of time prescribed or allowed is 10 days or less, intermediate Saturdays, Sundays, and legal holidays shall be excluded.

(b) Extension. The district court for good cause shown may upon motion extend the time prescribed by these rules or by its order for doing any act, and may thereby permit an act to be done after the expiration of such time if the failure to act was excusable under the circumstances; except the time for filing a notice of appeal shall not extend more than 10 days past the time prescribed for filing a notice of appeal under Rule 5. The motion must be made before the expiration of the period originally prescribed or extended by previous order of the court.

(c) Additional time after service by mail. Whenever a party is required or permitted to do any act within a prescribed period after service of a notice or other paper and the notice or other paper is served by mail, 3 days shall be added to the prescribed period.