You might try making a column for a max inventory amount then
you could in you on order column subtract max amount from current balance
Column A Formula =D2-C2
A B C D
1 "on order" received current balance MaxAmount
2 100 50 50 150

"cac1966" wrote:

I have a worksheet that shows inventory of a particular item. This sheet
shows the item on order, received and a current balance. My question is how
would I continue to keep introducing qunatities into the "on order" column
without having to add up the quantity on a calculator and then replacing the
number. Is there some way for this particular cell to remember the previous
number and then add the new quantity to it? This item is ordered on a
regular basis.

"on order" received current balance
100 50 50