'Twenty' in the Bible

These were the descendants of Levi according to their families, that is, the leaders of families as counted and individually listed who carried out assigned tasks in the Lord's temple and were twenty years old and up.

According to David's final instructions, the Levites twenty years old and up were counted.

David did not count the males twenty years old and under, for the Lord had promised to make Israel as numerous as the stars in the sky.