1159.6. Where the taxation year of a financial institution referred to in subparagraph a of the first or second paragraph of section 1159.3 covers a period of less than 359 days, subparagraph i of subparagraph a of the first or second paragraph, as the case may be, of the said section shall be construed as though the amount determined thereunder were equal to such proportion of the amount that would otherwise be determined thereunder as the number of days in its taxation year is of 365.