HOW OLD WAS AHAZIAH WHEN HE BEGAN TO REIGN?

II 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. (KJV) II 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. (KJV)

The original Hebrew for 2 Chr 22:2 said that Ahaziah was the son of forty-two years (the word for 'old' in that passage, 'ben', denotes sonship). This implies that one of his parents was 42. Since his father is implied to be 40, it was probably his mother that was 42.  This is a contradiction only in translation, not in what was originally written. Therefore, it is not a contradiction.