Hi CrazyDiamond7,
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.
--Percy