Which number between 20 and 29 has 2 and 3 in its prime factorization

If it has 2 and 3 in its factorization then it will be a multiple of 6.

24 is the only number between 20 and 29 that is a multiple of 6.

The long way would be to:

List the multiples of 2:

22, 24, 26, 28

List the multiples of 3:

21, 24, 27

The one that is both is 24.