Answer:
2 unit cubes of 7 units side length can fill the volume of the solid without overlap
Explanation:
Volume of a cube is L^3
Let the number of cubes be n
Since the cubes are similar,
then;
nL^3 = 686
nL^3 = 343 * 2
By inspection
L^3 = 343 (since it is a perfect cube and the cube root is 7)
n = 2