In Exodus 1:5, the Septuagint (the Greek translation of the Old Testament) and one manuscript among the Dead Sea Scrolls have the number seventy-five rather than seventy. Likewise, the Septuagint has the number seventy-five in Genesis 46:27, and lists an additional five descendants of Joseph in that passage (Genesis 46:20). Stephen, who was probably referring to the Septuagint, also speaks of seventy-five descendants in Acts 7:14. However, the Hebrew text of Exodus 1:5 (and Genesis 46:20–27) is likely correct. One piece of evidence is Deuteronomy 10:22, which also speaks of seventy descendants in both the Hebrew and the Septuagint.
5 All the descendants of Jacob were seventy persons; Joseph was already in Egypt.