Question

What is a counter example of the following conjecture?
Any number that is divisible by three is also divisible by six
A. 36
B. 27
C. 23
D. 18

Answer 1

I'm going with 27

Answer 2

Yes that's correct.
An integer is divisible by six (6) if and only if it is divisible by 3 AND by 2.
Since 27 is divisible by three and not by two, 27 is a counter example, and the only one among the four options, of the given statement:
`Any number that is divisible by three is also divisible by six`