ABC:2 Kings 8

Verse 25
The ReasonProject lists the following as a Bible contradiction with the headline "When did Ahaziah begin to reign?"

2 Kings 8:25 In the twelfth year of Joram the son of Ahab king of Israel did Ahaziah the son of Jehoram king of Judah begin to reign.

2 Kings 9:29 And in the eleventh year of Joram the son of Ahab began Ahaziah to reign over Judah.

Verse 26
Jim Meritt of Infidels.org claims there is a contradiction here in his section "How old was Ahaziah when he began to reign?" TheThinkingAtheist.com also claims this is a contradiction as does the Reason Project.

2 Kings 8:26 Two and twenty years old was Ahaziah when he began to reign; and he reigned one year in Jerusalem. And his mother's name was Athaliah, the daughter of Omri king of Israel.

2 Chronicles 22:2 Forty and two years old was Ahaziah when he began to reign, and he reigned one year in Jerusalem. His mother's name also was Athaliah the daughter of Omri.

Although other explanations exist, the most likely appears to be that posed by AiG's McKeever and Hodge of scribal error since older texts of 2 Chronicles 22 like the Syriac and Arabic actually have the correct number of 22, not 42. As pointed out by McKeever and Hodge:

"Many fail to realize that several ancient texts have 22 (or simply 20) instead of 42 as listed in the Masoretic Text (MT) in 2 Chronicles 22:2. The Syriac version (common to Eastern churches) and Arabic version each have 22. The Septuagint (LXX) has 20. In fact, the version used by the Antioch church in New Testament times was obtained by Archbishop Ussher at great cost and it had 22. These early translations were obviously drawing from another Hebrew text, different from what we know today as the Masoretic or standard Hebrew text used for most translations in modern times." -Stacia McKeever and Bodie Hodge, Answers In Genesis

This was originally pointed out by Dr. John Gill in John Gill's Exposition of the Bible in the 1700s:

"it seems best to acknowledge a mistake of the copier, which might easily be made through a similarity of the numeral letters, (bm), forty two, for (bk), twenty two; and the rather since some copies of the Septuagint, and the Syriac and Arabic versions, read twenty two, as in Kings; particularly the Syriac version, used in the church of Antioch from the most early times; a copy of which Bishop Usher obtained at a very great price, and in which the number is twenty two, as he assures us; and that the difficulty here is owing to the carelessness of the transcribers is owned by Glassius, a warm advocate for the integrity of the Hebrew text, and so by Vitringa: and indeed it is more to the honour of the sacred Scriptures to acknowledge here and there a mistake in the copiers, especially in the historical books, where there is sometimes a strange difference of names and numbers, than to give in to wild and distorted interpretations of them, in order to reconcile them, where there is no danger with respect to any article of faith or manners;" -Dr. John Gill, John Gill's Exposition of the Bible

Because other ancient texts have the correct number of 22, it appears a scribe simply made a mistake which crept into the Masoretic Text considered authoritative by many translators. However, the original text clearly did not have such a discrepancy/contradiction.