If your only concern is to display negative numbers as positive, this can be
done by creating a custom number format. But I would agree with the previous
posts and caution against doing this for any sheets that will involve
calculation, or will be used by anyone unfamilar with the custom formating.
It can be very difficult to debug a spreadsheet if the data you see is not
the same as the values that are stored, as it is usually not clear to other
users (or even to yourself after a few months have passed) when custom
formats are in use.
/* ending soapbox mode*/
The following custom format would show both positive and negative numbers
without and signs (and zeros as a dash):
#,##0;#,##0;"-";@
As another example, the following format would show positive values as
negative and vice versa, with 'Accounting' format style aligned parentheses:
(* #,##0);_(* #,##0_);_(* "-"_);_(@_)
To use these, just select a number format type of 'Custom' in the Format
Cells dialog box, and paste the format definintion into the 'Type' box.
Custom formats can give you great flexibility in the way data is shown, but
it is up to you to make sure they are used appropriately.
Good luck
TK