Ezra 6:15

(15) The third day of the month Adar, which was in the sixth year.—The event around which this part of the history revolves is dated with due care; it was on the third day of the last month of the ecclesiastical year, B.C. 516-515. Haggai (Haggai 1:15) gives the exact date of the re-commencement: the time therefore was four years five months and ten days. But, dating from the first foundation (Ezra 3:10), no less than twenty-one years had elapsed.