WordExchange

What are total number of combinations of 9 things taken 3 at a time?

(A) 18
(B) 27
(C) 48
(D) 84

The answer is: (D) 84
Combinations = [9!]/[3!(9-3)!] = [9.8.7.6!]/[3!.6!] = 504/6 = 84