8 years old because in part one sasuke was 13 and itachi 18. Giving that itachi killed his clan was he was 13 toi subtract 18 from 13 which gives toi 5 giveing the difference in age. Finally toi subtract 13 and 5 to get the finnaly answer of 8. Its a tough question toi cant find the answer any where soooo toi have to relay on figure it out another way
10 because Naruto was 10 when he left with jiraiya to train for two years and sasuke was older than Naruto and their team went on mission for 3 years unto sasuke left and their both 16 now.
