Jessie,
Let's take a look at what your "math" tells us about history.
If you are claiming a basic exponential growth model then the basic formula would be:
y=a*b^x/T
where:
a = your starting population (i'm guessing you propose 8 for post-Flood)
b = the growth rate (lets just say 2 so that we can model this formula after the population doubling, the opposite of a half-life).
x = the time at measurement
T = time it takes to double the population (see explanation for b)
By using this growth model we see that. . .
- the World population at the time of Joseph's slavery would have been 78 people (24 of whom were his brothers, sisters-in-law, father, mother and step-mother not including any sisters, cousins, nieces or nephews.)
- the World population at the time of the Exodus would have been 154 people
As you can see, a constant growth dynamic is inconsistent with your literal interpretation of genesis.