1 ¶ Now these are the names of the children of Israel, which came into Egypt; every man and his household came with Jacob. 2 Reuben, Simeon, Levi, and Judah, 3 Issachar, Zebulun, and Benjamin, 4 Dan, and Naphtali, Gad, and Asher. 5 And all the souls that came out of the loins of Jacob were seventy souls: for Joseph was in Egypt already. 6 And Joseph died, and all his brethren, and all that generation. 7 And the children of Israel were fruitful, and increased abundantly, and multiplied, and waxed exceeding mighty; and the land was filled with them.
Genesis 46: 26 All the souls that came with Jacob into Egypt, which came out of his loins, besides Jacob’s sons’ wives, all the souls were threescore and six; 27 And the sons of Joseph, which were born him in Egypt, were two souls: all the souls of the house of Jacob, which came into Egypt, were threescore and ten.
Deuteronomy 10:22 Thy fathers went down into Egypt with threescore and ten persons; and now the LORD thy God hath made thee as the stars of heaven for multitude.
Acts 7:14 Then sent Joseph, and called his father Jacob to him, and all his kindred, threescore and fifteen souls.
The difference in numbers between Moses’ accounts in Genesis, Exodus, and Deuteronomy, and Stephen’s account recorded by Luke in Acts can be attributed to counting different people such as wives not mentioned in one. There are a number of very good explanations for why Stephen would count 75 people leaving for Egypt with Jacob and Moses would say 70 three times.
Look at the factors by which this family of less than 100 people grew. First, there is no mention in the Bible of widespread epidemics or virulent diseases yet. The first known epidemic in scientific literature and history may have been a Typhus epidemic in Athens, Greece in the middle of the first millennium BC, which killed upwards of 100,000 people. It was brought on by war and as many as 30 different microbes have been blamed for it. We will see God placing epidemics directly upon the Egyptians and their livestock.
We will also see indications of a high birth rate and of the hardiness and health of the Hebrews who had come to this land. How fast can populations increase is not only a subject of debate but has been seen as populations arise from great calamity. A high birth rate and abundant food resources can lead to relatively quick growth in population. When resources are abundant a population can experience what is called “exponential growth” and this leads to a rapid multiplication of individuals. If you add God’s supernatural purpose for multiplying the children of Israel you can imagine how amazing this could be.