2^3 * 3^1
Go step by step. 24 = 2 x 12. 12 = 2 x 6. 6 = 2 x 3. We can't factor any more.
Therefore, we have 12 = 2 x 6, and since 6 = 2 x 3, we get 12 = 2 x 2 x 3.
Then 24 = 2 x 12, and 12 = 2 x 2 x 3, so 24 = 2 x 2 x 2 x 3.
There are 3 2's and 1 3's, so it's 2^3 * 3^1.
Hope that helped,
-sirswagger21