(3)Where the chargeable accounting periods of the principal and subsidiary are not co- terminus, such division and apportionment of the profits or losses of the subsidiary for any chargeable accounting period shall be made as will allocate the due proportion thereof to the relative chargeable accounting period or periods of the principal; and such division and apportionment shall be by reference to the proportion that the number of days of the chargeable accounting period of the subsidiary falling within the relative chargeable accounting period or periods of the principal bears to the total number of days in the chargeable accounting period of the subsidiary.
