In how many ways can 8 Bangladeshi, 4 American, and 4 Japanese be seated in a row so that all people of the same nationality sit together?

Question: In how many ways can 8 Bangladeshi, 4 American, and 4 Japanese be seated in a row so that all people of the same nationality sit together?

Solution:
Taking all people of the same nationality as one person, then we will have only three people.
These three people can be arranged themselves in = 3! Ways
8 Bangladeshi can be arranged themselves in = 8! Ways
4 Americans can be arranged themselves in = 4! Ways
4 Japanese can be arranged themselves in = 4! Ways

Hence, the required number of ways = 3! 8! 4! 4! Ways