Question:
In how many ways can six persons be seated in a row?
Solution:
Number of seats available to the first person = 6
Number of seats available to the second person = 5
Number of seats available to the third person = 4
Number of seats available to the fourth person = 3
Number of seats available to the fifth person = 2
Number of seats available to the sixth person = 1
Total number of ways of making the seating arrangement $=6 \times 5 \times 4 \times 3 \times 2 \times 1=720$