Noahs grand father
Ge:5:21: And Enoch lived sixty and five years, and begat Methuselah:
Ge:5:22: And Enoch walked with God after he begat Methuselah three hundred years, and begat sons and daughters:
Ge:5:25: And Methuselah lived an hundred eighty and seven years, and begat Lamech:
Ge:5:26: And Methuselah lived after he begat Lamech seven hundred eighty and two years, and begat sons and daughters:
Ge:5:27: And all the days of Methuselah were nine hundred sixty and nine years: and he died.
The year then is still the same today, only they observed a lunar month which never changes. Lunar month is the rising and setting of the moon phases.A month would be 360/12 = 30 days .