A box (cube) has all equal edges or sides (s), thus the volume (v) of the cube is:
[tex]v = {s}^{3} \\ 27 \: {in}^{3} = {s}^{3} \\ \sqrt{( {s}^{3}) } = \sqrt{( {27in}^3)} \\ s = 3 \: in[/tex]
So since each side or edge around is 3 in, then the length around the square bottom of the box = 4×3 = 12 in