To maintain an audit trail, I would use a separate column (or columns as the case may be). Suppose your data are in a single column (A) starting with A2. Then, in B2, enter =-A2.I have a similar issue. I copy and paste data into excel from another program, but the program I copy from displays everything as its opposite value. So I need to be able to convert all the positives to negatives and vice versa in Excel. I've tried using the suggestions above and they do work great for converting negatives to positives, but the positives stay positive. I'd really appreciate any ideas!