Folks, I've been asked to develop a simple spreadsheet which measures the
amount of product stored in a Tank. The calculation starts with an opening
stock, some product might be removed and other product might be received. A
simple calculation ensues, which gives rise to a closing stock. However,
I've now been asked to incorporate a manual adjustment field, which could be
either a plus or a minus figure.

I wonder if someone out there can help me with this. I'm not sure how to
write the formula for this extra step in the calculation.

Here's an example:
Starting stock 1000
Received 200 (+)
Despatched 300 (-)
Closing Stock 900
Manual adjustment +5 making closing stock 905
or
Manual adjustment - 5 making closing stock 895

Thanks (Hope this is understandable)