=SUM(1*(FREQUENCY(IF((A1:A10<"")*(A1:A10="0001"), B1:B10),B1:B10)0))

this is an array formula, so commit with Ctrl-Shift-Enter, not just Enter.

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HTH

Bob

(there's no email, no snail mail, but somewhere should be gmail in my addy)



"Chris Gorham" wrote in message
...
Hi,

I have 2 columns of data...as follows

Col A Col B

0001 123
0001 123
0001 111
0002 146
0002 146
0003 234
0003 234
0003 100

I want to be able to count the number of unique entries in Col B using Col
A
as the criteria....

Answer

0001 2
0002 1
0003 2

and so on....

Probably an array function but not sure....any help appreciated

Chris