In how many ways the letters of word FACETIOUS can be arranged so that the first three letters are in dictionary order?

A 54000

B 56800

C 60480

D 62000

E 67200

Correct Answer: Option C

We see all letters of word FACETIOUS are different.

Take any three letters as first three letters. This can be done in 9C3 ways, i.e., 84 ways.

Now, for these first three letters, there is only one arrangement possible that is when they are in dictionary order.

Remaining 6 letters can be arranged in 6! Ways.

∴ Total number of ways = 84 × 6! = 60480