Formula Report Painter

Hi,

I have a formula creation problem. Like there is group of say 18 to 20 fields which I need to add them so the formula will be Y001+ Y002 + Y003 til Y020 right. so there are four such type of group have more then 15 fields to be added. So when I tied to run the report but it gave me error saying "Formula too long to be converted".

Can any give me sugesstion

Thanks in advance.

Kiran