'Forty one' in the Bible

So King Rehoboam strengthened himself in Jerusalem, and reigned, - because, forty-one years old, was Rehoboam when he began to reign, and, seventeen years, reigned he in Jerusalem, the city which Yahweh had chosen, to set his Name there - from among all the tribes of Israel, and, the name of his mother, was Naamah, the Ammonitess.