How to Convert Units for Coulomb's Law Equations

[kh199]

I have a real simple question. I'm doing a problem that involves Coulomb's law. My charge separation is 5 nanomeers, and the charges are each elementary.

So, for the equation, I have:

(9E9 (N*m^2/C^2) *(1.6E-19)^2 (C^2) ) / (5 nm)^2

Units are bolded. The denominator has to be converted to meters to it can cancel out with the units of K. Do I have to square the x10^-9 multiplier as well? Does the denominator end up as 2.5E-8 m^2 or does it end up as 2.5E-17 m^2

 

[CompuChip]

(5 nm)² = (5 nm) x (5 nm) = (5 x 10^-9 m) x (5 x 10^-9 m) = ... ?