What is the volume of a box that will hold exactly 567 of these cubes with 1/3 inch sides?

If the length, width, and height of the little cubies are 1/3 inch,
then the volume of each cubie is

             (1/3 inch) x (1/3 inch) x (1/3 inch)  =  1/27 inch³ .

If the box holds exactly 567 of them, then the volume
of the box is

               (567) x (1/27 inch³)

           =  (567 x 1 / 27) inch³

           =  (567 / 27) inch³  =  21 inch³ .