How old was Jehoachin when he began to reign?

How old was Jehoachin when he began to reign?
He was 18 years old and he reigned for 3 months.	He was 8 years old and he reigned for 3 months and 10 days.
2 Kings 24:8 Jehoiachin was eighteen years old when he began to reign, and he reigned in Jerusalem three months.	2 Chronicles 36:9 Jehoiachin was eight years old when he began to reign, and he reigned three months and ten days in Jerusalem.