C. F. Keil and Franz Delitzsch on 2 Chronicles 22:2

2Ch 22:2

The number 42 is an orthographical error for 22 (ב having been changed into )מ,   2Ki 8:26. As Joram was thirty-two years of age at his accession, and reigned eight years (2Ch 21:20 and 2Ch 21:5), at his death his youngest son could not be older than twenty-one or twenty-two years of age, and even then Joram must have begotten him in his eighteenth or nineteenth year. It is quite consistent with this that Joram had yet older sons; for in the East marriages are entered upon at a very early age, and the royal princes were wont to have several wives, or, besides their proper wives, concubines also. Certainly, had Ahaziah had forty-two older brothers, as Berth. and other critics conclude from 2Ki 10:13., then he could not possibly have been begotten, or been born, in his father’s eighteenth year. But that idea rests merely upon an erroneous interpretation of the passage quoted; see on 2Ch 22:8. Ahaziah’s mother Athaliah is called the daughter, i.e., granddaughter, of Omri, as in 2Ki 8:26, because he was the founder of the idolatrous dynasty of the kingdom of the ten tribes.