In how many ways can letter of the word RAILINGS arrange so that R and S always come together?

Dear Student,

Please find the below required solution.

The number of ways in which the letters of the word RAILINGS can be arranged such that R & S always come together is

Since R & S as only 1 letter so that RS or SR can be arranged = 7! x 2!

But in given word RAILINGS, I repeated for 2 times

Hence the word RAILINGS can be arranged such that R & S always come together = (7! x 2!)/2! = 7! = 5040 ways.
 

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