Reverse value in a column
 

You need a helper column so assuming you numbers are in column A type this in
B1 and drag down as required.

=IF(A1<0,A1,A1*-1)

Mike

"rb" wrote:

If I have a column with numbers and there are both positive and negative
numbers and I want to change all positive numbers to negative in one formula.
I know how to change negative into positive.