Asealed rectangular box measuring 6 x 8 x 18 contains 864 sugar cubes, each measuring 1 x 1 x 1. how many of the sugar cubes are touching the box?

This question is just giving you a fancy way of finding the surface area.

Surface area is 2(L)(w) +2(L)(h)+2(h)(w)

Plug into the equation

2(6)(8)+2(6)(18)+2(18)(8)
=96+216+288
=600

Maybe the answer is 20mm. all i really did was just multiply, which is obvious.