The Governing Council of Seventy

Seventy is not a round number in the Bible. It is a count.
Israel's elders number seventy. The nations disinherited at Babel number seventy. And in the Ugaritic material from just over the border, the divine council had seventy sons. Israel's seventy elders are the earthly counterpart of a heavenly arrangement, and a polemic against the pantheon next door.
One honest caveat. The number is not textually settled - the Septuagint has seventy-two for the nations in Genesis 10. Seventy is the better-supported reading, not the certain one.
Scripture links:
- Exodus 24:9-10 - seventy elders go up and see the God of Israel.
- Deuteronomy 32:8-9 - the nations divided, with Israel kept as the Lord's portion.
God's household has a shape, and Israel's institutions were built to echo it.