Many thanks to mattjdohm, David and Roger.

I had begun to think that a summary sheet was part of the answer but
then David and Roger told me the syntax for the SUM function.

I couldn't quite believe that the SUM function would not do the trick.

Many thanks again.

In article , David Biddulph
<groups@[at] writes
Abolutely! Well spotted, Roger.

--
Stephen White )