This isn't the fanciest trick, but it is one that can save you some time.
Let's say you dump some financial data from your accounting system, and expenses come out as negative numbers. But for your report, you need them to be positive numbers. Here's what you can do.
1) Type "-1" in any cell. Copy the cell.
2) Highlight the numbers you wish to change from negative to positive (or positive to negative)
3) Paste -> Paste Special
4) Click "Multiply," then OK
That's it! All values are multiplied by -1. You an also use this same process to divide, add, or subtract all numbers by a specific value.
