Hi,

I'm trying to predict weight loss at hatching in some eggs I have in an
incubator. It's basically set out as day of incubation in one column and
weight of egg in another. What I'd like, is to ask for the projected weight
on a specific day in the future (always the same day). However, I want to be
able to keep entering data (say I've reached day 3 now, so I'd like to enter
day 4 tomorrow etc), so I need the formula to include empty cells (o I don't
have to change it every time I enter new data). This doesn't seem to be
working, I think the formula is including missing values as 0, which messes
up the calculation. The missing values are before the first values as well as
after.

Is there a way of getting excel to ignore the cells with missing values? I
should also mention that there are 8 eggs at the moment, and there will be
lots more. Id like to just create this formula once and for all, and just
drag it to wherever I need it.

Thanks for reading this. I hope one of you has a good solution to what I'm
sure is an easy problem to solve, right?

Regards

Ása