put -1 in a blank cell. Select the cell and do Edit=Copy

Select all the cells you want to change (including cells containing zero)
and do Edit=Paste Special and select Values and Multiply.

--
Regards
Tom Ogilvy

"me" wrote in message
...

How do you change the value of a number from positive to
negative and vice versa in excel 2000 ?

I need to do this with every number in the column. zeros
should be unaffected.

Thanks