1. Adam died within the "Day", (Gen. 2:17) or before 1,000 years (II Peter 3:8).
2. According to tradition, Adam had 33 sons and 23 daughters. By the time Seth was born to replace slain Abel (Gen. 4:25) world population could have been in the scores.
3. Those sons listed weren't necessarily the firstborn, but they did marry within their race (Caucasian), so that Noah was racially pure (Gen. 6:9).
4. Arabs and Jews have a tradition that Enoch invented writing.
5. Lamech died 5 years before the flood, and Methuselah, who had the longest recorded life span, died in the year of the flood, if not in the flood.
6. There were ten generations to Noah, the number of Judgement. The world was found guilty of sin and sentenced to death by drowning.
7. Noah begins to build the Ark, 120 years before the flood (Gen. 6:3), and his sons (Gen. 5:32).