Question

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

Answer 1

SSS are to be together. ie consider SSSS as a single free unit. 
remaining free units= (13 - 4) 
Total number of free units = (13 -4) +1= 10 free units 
10 free units can be arranged in 10 ! ways 
Internal arrangement of SSSS together = 4 ! ways 

Total number of arrangements = 10! x 4 ! = 87091200 ways 

But Identical permutations are= 87091200/(4! x 3! x 2! x 2!) =151200 ways