Try a little shorter Array_Formula:
http://img51.imageshack.us/img51/4248/nonamef.png
Micky



"Natalie Lau" wrote:

Hi

In my Excel worksheet there are two columns A & B. A contains the product
codes and B contains the customer codes. How can I count the number of UNIQUE
customer for a particular product? Both formula or pivot table would be fine.

Col A Col B
Pen Customer 1
Ruler Customer 1
Pen Customer 2
Ruler Customer 1
Pen Customer 1
Pen Customer 3

Thanks in advance!