The volume of a cube is 64. Its surface area is

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Volume of a cube is s^3 where s is the length of one side.
V = 64
s^3 = 64

Take the cube root of each side:
s = 4 since 4^3 = 64

Surface Area of a cube is 6s^2. With s = 4, we have:
SA = 6(4)^2
SA =6(16)
SA = 96