2 Chronicles 12:13
So king Rehoboam strengthened himself in Jerusalem, and reigned: for Rehoboam was one and forty years old when he began to reign, and he reigned seventeen years in Jerusalem, the city which the Lord had chosen out of all the tribes of Israel, to put his name there. And his mother’s name was Naamah an Ammonitess. (2 Chronicles 12:13)
One and forty years.
 Since Solomon reigned 40 years (ch. 9:30), Rehoboam was probably born the year before Solomon came to the throne.
Strengthened himself.
These words indicate Rehoboam’s recovery from the results of Shishak’s invasion.