In other words, count the unique *numbers* in C5:C10 where A5:A10 = A1?

If that's what you want try this array formula** :

=COUNT(1/FREQUENCY(IF(A5:A10=A1,B5:B10),B5:B10))

** array formulas need to be entered using the key combination of
CTRL,SHIFT,ENTER (not just ENTER). Hold down both the CTRL key and the SHIFT
key then hit ENTER.

--
Biff
Microsoft Excel MVP


"Fiona Yorke-Saville" wrote in
message ...
Hi
I wondered if anyone knew the formula for the following:-

If A5:A10 = A1, then count C5:C10, but do not count duplicate information
(such as there being 1234 in both call C5 and C6, only count this as 1)

Thank you