Enter 12/8 in A1 and 11/8 in B1
Select A1 and B1
Drag the right-bottom corner of B1 to right...

I tested with Excel 2007

"Jessica" wrote:

Hello,

How could I use the "fill series" to make my dates appear like this:

12/08, 11/08, 10/08, 9/08, 8/08, 7/08.......

I want to go backwards in time, left to right.

Thank you!