How many ways can 5 people be seated in 5 seats?
We have the permutation 5!.
Because the first seat can have 5 different people.
The next seat has 5 - 1 = 4 people since one person is in the first seat
The next seat can have 5 - 2 = 3 people since we have two people in the first two seats
The next seat can have 5 - 3 = 2 people since we have three people in the first three seats
The next seat can have 5 - 4 = 1 people since we have four people in the first four seats
Type in 5! into our search engine, and we get 120.
We have the permutation 5!.
Because the first seat can have 5 different people.
The next seat has 5 - 1 = 4 people since one person is in the first seat
The next seat can have 5 - 2 = 3 people since we have two people in the first two seats
The next seat can have 5 - 3 = 2 people since we have three people in the first three seats
The next seat can have 5 - 4 = 1 people since we have four people in the first four seats
Type in 5! into our search engine, and we get 120.