A cube with edge of length 4 is divided into 8 identical cubes. How much greater is the combined surface area of the 8 smaller cubes than the surface area of the original cube?

A) 48
B) 56
C) 96
D) 288
E) 384

The surface area of the original cube is 6\left(4^2\right)=96.

sube cut into 8 cubes

When the cube is cut into 8 smaller cubes (accomplished by cutting it in half along each axis, see above) then each cube has an edge length of 2, so each has a surface area of 6\left(2^2\right)=24. Because there are 8 of them, the total surface area is 8(24)=192.

The question asked “how much greater,” so we subtract: 192-96=96. This makes sense in an abstract way, if you think about it. By cutting a cube in half along each axis, you’re doubling the surface area.

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