You can use a formula like:
=SUMPRODUCT((A1:A10<"")/COUNTIF(A1:A10,A1:A10&""))
to count the number of unique entries in A1:A10.

You may want to look at Chip Pearson's site. He has lots of techniques to work
with duplicates:
http://www.cpearson.com/excel/Duplicates.aspx


Alan wrote:

How can I take a range (a1:a100) that ISN'T sorted and find the number of
unique entries?

--

Dave Peterson