Answer
100 meters
Work Step by Step
We know that in a normal atom, the proportion of the diameter nucleus to the diameter of the whole atom is $\frac{10^{-13}}{ 10^{-8}}$. So, we find that if we scale this whole fraction up by 10000, we get a new, but equivelent fraction, of $\frac{1}{ 10^5}$. So, if a nucleus was 1 millimeter in its diameter, the whole diameter of the atom would actually be equal to 100000, or 100 meters.
