HOW OLD WAS JEHOIACHIN WHEN HE BECAME KING?  HOW LONG DID HE REIGN?

II Kings 24:8 Jehoiachin was eighteen years old when he began to reign, and he reigned in Jerusalem three months. And his mother's name was Nehushta, the daughter of Elnathan of Jerusalem. (KJV) II Chronicles 36:9 Jehoiachin was eight years old when he began to reign, and he reigned three months and ten days in Jerusalem: and he did that which was evil in the sight of the LORD. (KJV)

Scholars agree that Jehoiachin was 18, not 8, and that the mistake in 2 Chronicles was due to a transcribing error. Mistakes of exactly ten were easy to make in the Hebrew number system (the difference between 18 and 8 is a single hook). Since this was most likely a transcribing error, it does not reflect what was in the original texts, so it would not count as a contradiction. As for the 'three months' versus 'three months and ten days', the author of 2 Kings was simply rounding off, which is not a contradiction. No contradictions here.