21 Joash was seven years old when he began to reign.
2 Kings 11:21 Cross References - ACV
2 Kings 11:4
4 And in the seventh year Jehoiada sent and fetched the captains over hundreds of the Carites and of the guard, and brought them to him into the house of LORD. And he made a covenant with them, and took an oath of them in the house of LORD, and showed them the king's son.
2 Kings 22:1
1 Josiah was eight years old when he began to reign, and he reigned thirty-one years in Jerusalem. And his mother's name was Jedidah the daughter of Adaiah of Bozkath.
2 Chronicles 24:1-14
1 Joash was seven years old when he began to reign, and he reigned forty years in Jerusalem. And his mother's name was Zibiah, of Beersheba.
2 And Joash did that which was right in the eyes of LORD all the days of Jehoiada the priest.
3 And Jehoiada took two wives for him, and he begot sons and daughters.
4 And it came to pass after this, that Joash was minded to restore the house of LORD.
5 And he gathered together the priests and the Levites, and said to them, Go out to the cities of Judah, and gather money from all Israel to repair the house of your God from year to year. And see that ye hasten the matter. However the Levites did not hasten it.
6 And the king called for Jehoiada the chief, and said to him, Why have thou not required of the Levites to bring in out of Judah and out of Jerusalem the tax of Moses the servant of LORD, and of the assembly of Israel, for the tent of the testimony?
7 For the sons of Athaliah, that wicked woman, had broken up the house of God, and also all the dedicated things of the house of LORD they bestowed upon the Baalim.
8 So the king commanded, and they made a chest, and set it outside at the gate of the house of LORD.
9 And they made a proclamation through Judah and Jerusalem, to bring in for LORD the tax that Moses the servant of God laid upon Israel in the wilderness.
10 And all the rulers and all the people rejoiced, and brought in, and cast into the chest, until they had made an end.
11 And it was so, that, at what ever time the chest was brought to the king's officers by the hand of the Levites, and when they saw that there was much money, the king's scribe and the chief priest's officer came and emptied the chest, and took it, and carried it to its place again. Thus they did day by day, and gathered money in abundance.
12 And the king and Jehoiada gave it to such as did the work of the service of the house of LORD. And they hired masons and carpenters to restore the house of LORD, and also such as wrought iron and brass to repair the house of LORD.
13 So the workmen labored, and the work of repairing went forward in their hands, and they set up the house of God in its state, and strengthened it.
14 And when they had made an end, they brought the rest of the money before the king and Jehoiada, from which were made vessels for the house of LORD, even vessels with which to minister and to offer, and spoons, and vessels of gold and silver. And they offered burnt offerings in the house of LORD continually all the days of Jehoiada.