Question

How many different ways can the letters of “football” be arranged

Answer 1

Answer:   10,080

Explanation:

There are 8 letters so there are 8! = 8*7*6*5*4*3*2*1 = 40,320 permutations of those letters. However, the letters "O" and "L" show up twice each, so we must divide by 2! = 2*1 = 2 for each instance this happens.

So,

(8!)/(2!*2!) = (40,320)/(2*2) = (40,320)/4 = 10,080

is the number of ways to arrange the letters of "football".

The reason we divide by 2 for each instance of a duplicate letter is because we can't tell the difference between the two "O"s or the two "L"s. If there was a way to distinguish between them, then we wouldnt have to divide by 2.