Charge Denisty

Hello Everybody,

   I'm trying to get the charge density and I read this in the documentation "The charge and spin density in the .charg_frm file are in the same units as those used by CASTEP during calculations. The values are normalized to the number of electrons per cell." How would I unnormalize this as it were? How can I get the charge density at a given point?

   Thanks, 
     Josh