First, we need to find the volume of the prism, which is found by multiply the cross-sectional area by the length
(3 x 4.5) x 6 = 81 cm³
Now, we need to work out the volume of one of the little cubes, found by raising the side length to the power of 3
0.5³ = 0.125 cm³
Now, all we have to do is divide the larger volume by the smaller volume to find the number of cubes we need to fill the prism up.
81/0.125 = 648 cubes
Hope I helped!! xx