Gen 5:27 says that Methuselah was 969 years old when he died. Gen. 5:26 says Methuselah lived 782 years after he begat Lamech. This means he was 187 years old when he begat Lamech. Gen 5:28-29 says that Lamech was 182 when he begat Noah. This means that Methuselah was 369 years old when his grandson, Noah was born. Gen 7:5 says Noah was 600 years old when the flood came upon the earth. If Noah's grandfather, Methuselah, was 369 years old when Noah was born and Noah was 600 when the flood came then Methuselah would have been 969 years old when the flood came. He was 969 when he died, Gen 5:27, which is to say that he died in the year of the flood and could have died in the flood.