How old was Jehoiachin when he became king? 2 Chronicles 36:9 and 2 Kings 24:8. The correct age of Jehoiachin was 18, not 8.
- Eight years old: 2 Chron. 36:9, “Jehoiachin was eight years old when he became king, and he reigned three months and ten days in Jerusalem, and he did evil in the sight of the Lord.”
- Eighteen years old: 2 Kings 24:8, “Jehoiachin was eighteen years old when he became king, and he reigned three months in Jerusalem; and his mother’s name was Nehushta the daughter of Elnathan of Jerusalem.”
Obviously, Jehoiachin was 18 when he began his rule since it says he did evil in the sight of the Lord which suggests maturity and responsibility.
The discrepancy in ages is probably due to a copyist error. We can see that the difference in ages is 10 years. The system of number notation used by the Jews at the time of Ezra consisted of horizontal hooks that represented values of ten. 
would equal the number 14 where would be 24. If one or both of the hooks were smudged or flaked off of papyri, then the dates would be off by values of 10 years.
Does this mean the Bible is not trustworthy? Not at all. Inspiration is ascribed to the original writings and not to the copies. Scribes made errors. However, the errors were very infrequent and from other information in the Bible, we can easily ascertain what the correct age is.
Another possible explanation is that the difference of 10 years from the two different texts could be that he began to rule with his father at the age of eight but did not take complete control until the age of 18, a 10-year difference.
