'Twelve' in the Bible

Jehoram the son of Ahab became king over Israel in Samaria in the eighteenth year of Jehoshaphat king of Judah, and reigned twelve years.

Manasseh was twelve years old when he became king, and he reigned for fifty-five years in Jerusalem. His mother’s name was Hephzibah.

He got rid of the idolatrous priests whom the kings of Judah had ordained to burn incense [to pagan gods] in the high places in Judah’s cities and all around Jerusalem—also those who burned incense to Baal, to the sun, to the moon, to the constellations [of the zodiac], and to all the [starry] host of heaven.