>Septuagint
There are differences between the septuagint and the masoretic texts about the age of Methuselah at the time of the flood. The LXX makes it appear as if Methuselah survived the Great Flood which is not possible:
LXX: Methuselah lived to be 969 years old (Genesis 5:27)
MAS: Methuselah lived to be 969 years old (Genesis 5:27
LXX: Meth. 167 years old when Lamech born (Gen 5:25)
MAS: Meth. 187 years old when Lamech born (Gen 5:25)
LXX: Lamech 188 years old when Noah born (Gen 5:28)
MAS: Lamech 182 years old when Noah born (Gen 5:28)
LXX: Noah 600 years old when flood began (Gen 7:6)
MAS: Noah 600 years old when flood began (Gen 7:6)
LXX: 167+188+600=955 years old when flood began
MAS: 187+182+600=969 years old when flood began
http://ecmarsh.com/lxx-kjv/genesis/gen_005.htm
Thus, according to the LXX, Methuselah lived another 14 years after the flood began.