Thanks for your answer zyzzyva57!

This seems to be in the right direction!

In my formula there is a problem that if C7 (in your file) equals to zero then the total result will contain a division by zero. so I tried to experiment in your formula so that C7 would be omitted if it gets the value zero and it worked!

So now there is actually only a small problem left. I shall try to use that nice "conditional formating" of yours in my own spreadsheet. Being a n00b I'm not sure that I'll fix it but I shall try!

One question I have directly is: Can I choose to omit more than one term? e.g can I choose to omit even the C8-term (if being zero) in the same line as this: =OM(C7=0;(C3*C4*C5)*(C8+C9);C3*C4*C5*(C6/C7+C8+C9)) ?

(by the way.. what does OM mean ?)

thanks again /gmyls