Charge in a Parallel Plate Capacitor

%% Charge in a Parallel Plate Capacitor
% This code will determine the charge and additional charge of a
% parallel plate capacitor. Notes and clarification are found at the
% bottom.

% Constants
E = 8.85*10^-12

% Inputs and Variables
SA = input('What is the surface area in m^2?\n');
d = input('What is the plate separation in meters?\n');
V = input('Voltage from the battery?\n');
% Optional variable for additional charge
Er = input('What is the relative permittivity?\n');

% Equations and Outputs
C = E*SA/d;
q = C*V;
qAdd = q*(Er-1);
fprintf('The charge stored is %e and the addition charge is %e', q, qAdd);

%{
The relative permittivity is an additional variable that is not needed to
calculate the charge stored.
Plugging in a 1 will result in additional charge to be 0 and plugging in a
2 will result in the same answer for additional charge.
%}