In how many ways can 3 people be seated in a row containing 6 seats?

Question: In how many ways can 3 people be seated in a row containing 6 seats?

Solution:
First person can be seated in 6 ways, the second person in 5 ways and the third person in 4 ways.
Then, by fundamental principle, total number of ways in which three persons can be seated in 6 seats in a row is (6 × 5 × 4) ways
= 120 ways