Getting back into math and currently stumped, not sure what I'm not getting here:
If I'm calculating the volume of a geometric object, say a sphere, I use the equation V = (4/3 * pi * r^3). However, the volume value will change depending on the value I use for the radius, i.e. 21mm (volume is much larger) vs 0.021m (volume is much smaller). I would assume the radius of the sphere is equal in both cases. How do I know which values to use, or what conversions to apply to get the same volume for calculations?