One way:

Assume your range is A2:A10. A3, 5, 7, 9 are empty

Select the range
Hit function key F5
Click the Special button
Select Blanks
OK

All the empty cell *within* the range are now selected and cell A3 is the
active cell.

Enter this formula in the formula bar:

=OFFSET(A3,-1,,)*-1

Hit CTRL ENTER

That will fill the empty cells *within* the range leaving the last entry to
be done manually (should be no big deal!)

Biff

"andresg1975" wrote in message
...
i have a column containing numbers, every other row there is an empty row,
i
would like to copy the cell from above with the opposite sign to that
empty
row, how can i do that with a formula or macro. So that i don't have to do
that one by one. Thanks a lot.