Running Total Formula in a Single Cell

I am creating a spreadsheet for inventory use. I want to have a running total in (1) cell based upon a new/different number being entered into a different cell.

Column B, Row 1 (This will be a new/different number entered every day - inventory in or out, so positive or negative number)
Column D, Row 1 (This will be a running total based on numbers inserted in previous 2 columns)

Basically what I have is a key inventory. So there is column A with key number, B should be keys IN, C should be keys OUT, or ideally B would be IN and OUT meaning, for inventory IN input a positive number and for inventory OUT input a negative number, and D Should be total.

Column E represents number of keys currently in the inventory. I was going to hide the current inventory column so all you see is IN/OUT and total.
So what I need is to be able to just come in and type in a number in the IN and/or OUT column, without having to add/subtract it with the number already in that column.

Bottom line, I’d like to be able to use IN and/or OUT columns to just type in numbers as they come and not have to worry about what’s already in those columns and get correct total number.

Can someone please help me with this?

Thanks!

Originally Posted by Richard Buttrey

Hi,

You'll need to upload an example workbook showing both data and results that you have manually entered. Tell us which cells are data and which are results and tell us the rules that you've used to arrive at the results.

Ok here it is. Attached worksheet shows
Column A - Key Numbers...No data value
Column B - Inventory IN
Column C - Inventory OUT
Column D - Total
Column E - Current Inventory(Starting point)

So the formula I used to get what i currently have is (=B2-C2+E2). This way whatever i input in columns C and C. totals out in D. But this way every time I want to add/subtract a number in B and C, i have to add to the number already in the column. I'd like to be able to type in a number in B and C as i go and still have a correct total. I wouldn't mind having just one column for in/out and use positive and negative numbers to differentiate inventory in or out.

I hope this makes sense. Thanks

Help Please!!!