Gen 8:13-14

Gen 8:13 and 14.—Noah was in the ark one solar year. He entered it on the 17th day, in the 2nd month, in the 600th year of his life, and quitted it on the 27th day of the 2nd month, in the 601st year of his life. The Jewish months were lunar, and the first six months of the year had 30 days each, and the latter six had 29 each, making altogether 354 days—add to this 11 days (i.e., the difference between the 17th, the day on which he entered, and the 27th, the day on which he quitted the ark) and we have 365, which constitute one complete year.
1882 Christadelphian p 82