Given a $d$-dimensional box, using only orthogonal cuts and not weird cuts to try to be 'creative', it takes $\sum\limits_{i=1}^{d}\lceil \log_2(s_i)\rceil$ cuts given that the sidelengths of the box are $(s_1,s_2,...,s_d)$. For example, the minimum number of cuts to turn a cube with side lengths of $4$ into $64$ unit cubes would be $2+2+2$ (from the formula above), giving $6$ cuts. I'll put a copy of the formula below for aesthetic purposes.
$$\sum\limits_{i=1}^{d}\lceil \log_2(s_i)\rceil$$
I don't need to understand the abstract explanation for dimensions higher than $3$, but can somebody please explain how a formula like this is derived from a problem like this?