For example(I created this)
An engineer is making a cube with a side of 5. He wants to place another cube inside it, but to make it fit, he made the side in the length of 4. Find the remaining space inside the cube.
V1(side 5)=s³
=5³
=125
V2(side 4)=s³
=(4)³
=64
V1-V2=125-64=61 cubic units.
Hope this helps =)