The part where you got 1728 as the volume for the cube is right, but the question is asking how many 2x2x2 meter cubes can fit, meaning that you must find the volume of the meter cubes and divide the cube with a volume of 1728 to get the amount of cubes. In this case 2^3 is 8, so 1728 divided by 8 is 216, which means that 216 meter cubes with 2x2x2 dimensions can fit inside the larger cube.
