In how many ways can the letters of the word ASSASSINATION be arranged so that all the S's are together?

The word ASSASSINATION consists of 13 letters including three As, four Ss, two Ns and two Is.

Considering all the Ss are together or as a single letter, we are left with 10 letters. Out of these, there are three As, two Ns and two Is.

Number of words in which all the Ss are together = Permutations of 10 letters of which three are similar to the first kind, two are similar to the second kind and two are similar to the third kind $=\frac{10 !}{2 ! 2 ! 3 !}=151200$