'Thirty' in the Bible

Then the king commanded Ebedmelech the Ethiopian, saying, Take from hence thirty men with thee, and take up Jeremiah the prophet out of the dungeon, before he die.

In the eighteenth year of Nebuchadrezzar he carried away captive from Jerusalem eight hundred thirty and two persons:

On the twenty-fifth day of the twelfth month of the thirty-seventh year of the exile of Judah’s King Jehoiachin, Evil-merodach king of Babylon, in the first year of his reign, pardoned King Jehoiachin of Judah and released him from prison.