  A latin hypercuboid of order $N$ is an $N\times...\times N\times k$ array
filled with symbols from the set $\{0,...,N-1\} $ in such a way that every
symbol occurs at most once in every line. If $k=N$, such an array is a latin
hypercube. We prove that any latin hypercuboid of order 4 is completable to a
latin hypercube.
  Keywords: latin hypercube, n-ary quasigroup
