OTWO - about 130 years you are right on the math. I think I said that because in my head I was remembering Babel. From the time of the flood to Babel was about 110-130 years according to genealogies in the Insight book.
So that means that in just 130ish years, 8 people became enough to build a massive tower to the heavens. A tower so scary that god wondered what they could accomplish and confused their languages. Never mind that the bible says it took hundreds of thousands of workers to build just the temple in Solomon's time. The Insight book does some crazy math and points out that there could have been 4,000 people alive if everyone started having kids young and continued until eighty years old. Even if that's possible to have kids until old age, 4,000 people stayed all together and didn't spread and built cities and a tower to heaven?
lol