Hi Becky,
Do conditional formating, position yourself in A1 then conditional
formating, where the formula is enter
A3=0
Then choose the format you want and done
You'd want to change to =$A$3=0 (or =A$3=0) if all 600 rows are to be
formatted based on the content of A3.
If the format of A1 is to be based on A3, and each cell's format is to based
on the format of the cell 2 rows down, it stays as =A3=0.