'Eighteen' in the Bible

Eighteen years after King Josiah had begun to reign, the king sent Azaliah's son Shaphan, grandson of Meshullam the scribe, to the LORD's Temple. He told him,

Jehoiachin became king at the age of eighteen years, and he reigned for three months in Jerusalem. His mother was named Hausa. She was the daughter of Elzaphan of Jerusalem.

The height of one of the pillars was eighteen cubits, and the capital on top of it was three cubits high. A latticework carved in the form of pomegranates encircled the capital, crafted completely out of brass. The second pillar was identical to the first.