Joash was seven years old when he began to reign, and he reigned forty years in Jerusalem. His mother's name also was Zibiah of Beersheba.
878-839 Joash Joash is merely an abbreviation of Jehoash
2 Kings 11:21 Seven years old was Jehoash when he began to reign.
2 Kings 12:1 In the seventh year of Jehu Jehoash began to reign; and forty years reigned he in Jerusalem...
1 Chronicles 3:11 Joram his son, Ahaziah his son, Joash his son,
seven years old As Joash was hidden six years in the temple, and was but seven when he came to the throne, he could have been but one year old when secreted by his aunt.