cumulative data in a column

[shyamvinjamuri]

I have Yesterday's date in column A, Today's data in column B. Column C has difference between column A and column B. Some days data changes many times a day.
How to put cumulative data in column D only when column C changes?

eg.
Today
10 in column A, 6 in column B, so column C is 4.
Tomorrow
column A is 25 column B is 20, so column C is -5.

I like to have column D showing -1 and so on every time I update the data in columns A and B. Column D should change only when values in column C change.

Please help.

Thanks

 

[Joe4]

Do you mean something like this?

If your data starts in row 2,
then enter this in the following cells:
D2: = C2
D3: =IF(C3<>0,D2+C3,"")
and copy the formula in D3 down for all rows