It almost sounds like you want to substitute a simplistic math equation for estimates that take into account climate, technology, agriculture, migration patterns, etc. A fixed math equation uninformed by what was actually going on in the real world at the time seems doomed to be inaccurate, even wildly so.
You've posted this same request a number of times, I don't think you're going to get a different answer, plus it's getting boring. If you respond to some of the objections you're getting maybe we could address what you think the problems are.
Re: The Flood story only works as a parable. — Things are not as they seem to be
One might understand and verify that every population data from past years does show a multiplication rate...
But not a constant multiplication rate. From actual population data over time you can calculate the rate of population increase for any period, but different time periods will have different rates, and in the absence of population data you can only guestimate. Your population projections are based upon guesses rather than data and so have little or no value.