=SUMPRODUCT(--(A2:A20=B2:B20),--(A2:A20<""),--(B2:B20<""))

--

HTH

RP
(remove nothere from the email address if mailing direct)


"Lingyan Hu" <Lingyan wrote in message
...
Imagine there are two columns of cells, each row of two cells are
corresponding to each other. How to find out the number of rows where the
two
corresponding cells have the same value?