I am putting together a medication inventory sheet. The fields I am trying to
calculate are as follows:

C Units Issued
G Units Added
H Total Units in Stock
L Yearly Total

What I would like to do is keep a running inventory total. I want to have
the Total Units in Stock to be the sum of the Units Added minus the Units
Issued which I can do. However,I need to then have the Total Units in Stock
remain constant and be continually updated after each calculation is
performed. As of right now every time I change Units Added or Units Issued
the Total in Stock changes only to reflect the two new number I entered. I
need to have the Total in Stock reflect the sum of the current Units Added -
Units Issued as well as the sum of the previous Total in Stock calculation.
Any help is greatly appreciated.