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 ...... .

The given word ie 'SYLLABUS' having letters SS, LL,ABUY.Now, number of ways to select two like letters are  2C1.And number of ways to select two distinct letters are 5C2And number of ways to permutate the 2 like letters and 2 distinct letters is 4!2!So, number of required words=2C1×5C2×4!2!=2×10×12=240