Question

how many diferrent 9-letter words (real or imaginary) can be formed from the letters in the word ECONOMICS?
the ans. must be 90,720

Answer 1

There are two C's, two O's, and one each of seven other letters: E, N, M, I and S. If you think of the C's as C1 and C2 , and the O's as O1 and O2, there are 9! = 362,880 possibilities. You must divide that by 2!*2! = 4 because four possible ways of placing the O's and C's are indistinguishable. This leaves you with
90,720.

The answer is 9!/(2!*2!)

Answer 2

90,720

Answer 3

nah