Today’s chapter has a genealogy in the middle of it. After listing the children of each of Jacob’s sons, grouped by mother, it gives the final count of family members as 70. At this time, I don’t think it would be a particularly good use of my time to check the narrator’s math. His point is that these are the people who ended up living in Egypt. After all, this is the chapter that reunites the family and gathers them all in Egypt; this is the home stretch of the story of the patriarchs.