SUMPRODUCT can be used to do more than multiply, when one evaluates
conditionals in ranges as Bob did.

However, you'd have to add an additional term to Bob's formula for the
date to get what you asked for. That might be difficult given your data
layout.

In article ,
Peledon wrote:

I didn't get this to work out what was required unforunately. I don't want
to multiply. However I have managed to work everything out by using a pivot
table. Thank you for your time.