Question

How do I know which is not a composite number

Answer 1

29

Explanation:

27 has factors of 9 and 3, so it is composite.

28 had factors of 2, 4, 7, 14, so it is composite.

29 is prime, so it is the answer.

Answer 2

29

Explanation:

To find what isn't a composite number, we need to find which of these is prime. 27 isn't since its 9*3. 28 isn't since its 14*2. 29 is prime