16.
“In the twenty and seventh year of Jeroboam king of Israel began Azariah son of Amaziah king of Judah to reign” (2 Kings xv, 1).
From the death of Ahaziah to the accession of Azariah the reigns of Israel’s kings were: Jehoram 12 years, Jehu 28 years, Jehoahaz 17 years, Joash 16 years, Jeroboam 27 years. 12 years + 28 years + 17 years + 16 years + 27 years = 100 years.
From the death of Jehoshaphat to the accession of Azariah the reigns of Judah’s kings were: Joram 8 years, Ahaziah 1 year, Athaliah 6 years, Joash 40 years, Amaziah 29 years. 8 years + 1 year + 6 years + 40 years + 29 years = 84 years.
If from the death of Ahaziah to the accession of Azariah was one hundred years, and from the death of Jehoshaphat to the accession of Azariah was eighty-four years, Jehoshaphat therefore died sixteen years after Ahaziah died.