Hi ,
You need to decide when the result should be positive and when it should be negative.
For example , if you have data in 2 columns A and B , you may choose to decide that you will subtract the data in column B from the data in column A. In this case , the formula to be put in , say column C , starting from cell C2 , would be :
=A2 - B2
Copy this formula down.
When the data in column A is bigger than the data in column B , the result will be positive , otherwise the result will be negative.
Instead , if you change the above formula to :
=B2 - A2
and copy this down , the result will be vice-versa.
Narayan