I did another population growth calculation using the Israelites in Egypt, the 400 years of captivity, and a growth rate of three children per couple, with a reproductive period of thirty years (three children born per couple in the ten year reproductive period between ages 20 and 30).
Not counting Joseph there were 11 couples to start with.
Years
1- 22 people (if the Israelites didn't bring any children from Canaan)
30- 33
60- 99
90- 297
120-891
150-2,673
180-8,019
210-24,057
240-72,171
270-216,513
300-649,539 I'm guessing it was about this time the Egyptians began to get nervous.
330-1,948,617
360-5,845,851
390-17,537,553
Based on how many came out of Egypt even this number is way too high, but demonstrates that even a modest reproductive rate adds up over time to a lot of people.
The bible states that 600,000 adult men along with their families came out, therefore, 600,000 adult men+600,000 wives+1,800,000 children=3,000,000 total. Many believe that Israel numbered between 3 and 5 million at the time of the exodus, which is a very reasonable number given the entire circumstance of their sojourn in Egypt and the fertile land of Goshen (where they actually lived and prospered).