If n is a natural number, then (6n^2 + 6n) is always divisible by
Options:
(A) 6 only
(B) 6 and 12 both
(C) 12 only
(D) 18 only
(E) 12 and 18 both Stream of consciousness first, then make a decision:
(6n^2 + 6n) = 6n(n + 1), which is divisible by both 6 and 12, since n(n+1) is always even.
Thus, the answer is (B).