Question 1001500
The box contains {{{7*14*5=490}}} unit cubes forming a 7cm by 14cm by 5cm prism.
If you remove the cubes that are touching the box walls, you are removing
the top 1-cm layer and the bottom 1-cm layer of that prism,
the front 1-cm layer and the back 1-cm layer, and
the leftmost 1-cm layer and the rightmost 1-cm layer,
and you are left with a prism measuring
{{{7cm-1cm-1cm=5cm}}} by
{{{14cm-1cm-1cm=12cm}}} by
{{{5cm-1cm-1cm=3cm}}} .
That prism will be made of {{{5*12*3=180}}} unit cubes.
The unit cubes that touched the box with at least one face are the unit cubes removed:
{{{490-180=highlight(310)}}} .