You double the radius of a sphere. How does this affect the volume?

The volume of a sphere is defined as:

V = (4*pi*r^3) / 3

then, if we double the radius of the sphere (r=2r):

V = (4*pi * (2r) ^3) / 3

V = (4*pi * (2^3*r^3)) / 3

V = (4*pi*r^3) / 3*8

Then, the answer is that if you double the radius of the sphere, its volume is increased 8 times.