A classic counting problem is to determine the number of different ways that the letters of "personnel""personnel" can be arranged. find that number.

Answer: 90,720

Explanation:

1) Assume initially the all the letters are different.

2) The number of ways how you can arrange 9 letters is:

P (9) = 9! = 362,880 different arrangements

3) Now take into account tha the letter n is repeated so half of the arragements are repeated.

4) The same happens with the letter e.

5) That means that you have to divide by 2 two times to get the number of differente arrays:

=> 362,880 / (2 * 2) = 90,720