Question:
The number of words, with or without meaning, that can be formed by taking 4 letters at a time from the letters of the word 'SYLLABUS' such that two
letters are distinct and two letters are alike, is_________.
Solution:
$\mathrm{S}_{2} \mathrm{YL}_{2} \mathrm{ABU}$
ABCC type words
$=240$