Números 1:24

24 From the descendants of Gad: All the men twenty years old or more who were able to serve in the army were listed by name, according to the records of their clans and families.

24 Of the children of Gad, their generations, by their families, by their fathers' houses, according to the number of the names, from twenty years old and upward, all that were able to go forth to war;