Good idea, I shall try the MOREFUNC thing: I would expect an XLL solution to
be fast.

I have not tried that many different array formulae to see which one wins on
performance, the one in my example is
{=SUM(IF(LEN(A2:A11000)0,1/COUNTIF(A2:A11000,A2:A11000)))}

This array formula is the slowest of the different example solutions.

Charles
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"Harlan Grove" wrote in message
ps.com...
Harlan Grove wrote...
...
=COUNTA(UNIQUEVALUES(Rng))

where UNIQUEVALUES is from Longre's MOREFUNC.xll add-in in order to
consider XLL add-in functions as well.

That'll teach me to work from memory. Make that MOREFUNC.XLL's
COUNTDIFF function.