In this question, a 'word' is defined to be any set of letters in a row, whether of not it makes sense. Find how many different 'words' can be made using only 5 letters of the word SYLLABUS
I tried to separate them into 4 cases,
1) all different letters
2) 2 'S'
3) 2 'L'
4)2 'S' and 2 'L'