To create a cube, all edges must be the same length. This means that since one edge is 4 inches, all edges of the cube must be 4 inches. This will be a 4in x 4in x 4in cube.
We can solve this by finding the volume : 4in x 4in x 4in = 64 in^3 meaning that 64 1 inch cubes will be needed.
Answer: 64