Question

How many different arrangements of the letters in the word SCHOOL are there?
1,440
720
360

Answer 1

Take the total number of letters factorial as the numerator, so 6!, and the number of repeated letters factorial as the denominator, two Os so 2!, so you have 6!/2!

Note that if you had two different letters that repeat, you have to do separate factorials for the separate repeated letters. In this case there's just one, so you don't have to worry about that.