If you use the calculation option "The field is the ____ of the following fields:", nulll values and zero values are included as zero and the number of number of items use is the number of fields selected.
If you want a different calculation, then you will have to write a custom script to sum and count the fields you want to include in the calculation.
Thanks for the replay, GKaiseril. I didn't want the zero's in there. I was hoping for some help with the script. I'm not all that familar with JS.