1)
Which two years did he reign?
1.
Rashi: They were the second and third years of Asa.
2.
Radak (33): Nadav did not rule until eight years after Yaravam died. Or, he ruled, but his kingship was weak, and those years are not counted towards his reign. In the second year of Asa, i.e. after Asa's 10 years of serenity (Divrei ha'Yamim II, 13:23), Nadav became king.
