A cube has *** 12 sides, where the ball can't roll is where it has 12 sides, and where the ball can't touch the box is where it has eight corners and 12 sides. Assuming that eight balls are placed on the corners and half of them are cut parallel to the box, it can be seen that the bottom area that is not in contact with the edge except the corner is 6 MINUS 2 times the radius. There are still eight corners left, which together can be regarded as a cube with a length of 2CM and an inscribed ball. Calculate the volume of the cube and subtract the volume of the ball. Then add up the two results. I'm sorry I didn't make it clear, and I don't know if the method is right. It should be right ... Finally, I calculated things carelessly, and I don't know if there is anything wrong. If you understand it yourself, you can do the calculation again.