You can use Conditional Formatting. In your case:

1. Select A4.
2. Go to Format Conditional Formatting
3. Choose "Cell Value Is", then choose "Equal to" and put
0 in the third box.
4. Click the Format radio button and format pattern as
yellow.

To see more examples, go to:

http://www.contextures.com/xlCondFormat01.html

HTH
Jason
Atlanta, GA

-----Original Message-----
is there a way to put colors in a formula...for example,
if a4=0, the
background in a4 becomes yellow. ???
.