How many unit cubes are needed to make a model of a rectangular prism that is 4 units long, 3 units wide, and 2 units tall?

24 unit cubes.

Explanation:

To find this, you need to find the volume of the rectangular prism. To find volume, you multiply length times width times height. So, you multiply 4 x 3 x 2 which equals 24. So, you need 24 unit cubes to make a model of the rectangular prism specified.