Genesis, the Bible’s first book, says Methuselah lived 969 years, longer than anyone else it names.
It also gives the ages that link him to Noah. Methuselah was 187 when his son Lamech was born. Lamech was 182 when Noah was born. The flood came when Noah was 600.
Add those up and you get 969. So by the book’s own numbers, Methuselah died in the year of the flood.