Multiple Point Charges
The electric potential (voltage) at any point in space produced by any number of point charges can be calculated from the point charge expression by simple addition since voltage is a scalar quantity. The potential from a continuous charge distribution can be obtained by summing the contributions from each point in the source charge.
The calculation of potential is inherently simpler than the vector sum required to calculate the electric field.
 The electric field outside a spherically symmetric charge distribution is identical to that of a point charge as can be shown by Gauss' Law. So the potential outside a spherical charge distribution is identical to that of a point charge.

