Which is a counterexample to the conjecture?

Any number that is divisible by 3 is divisible by 9.

63

69

18

27

From the bottom up:

- - Is 27 a counter example? No. It's divisible by 3 and also by 9.

- - Is 18 a counter example? No. It's divisible by 3 and also by 9.

- - Is 69 a counter example? Yes! It's divisible by 3, but not by 9.

- - Is 63 a counter example? No. It's divisible by 3 and also by 9.