Hugh,
An interesting challenge.
Because you want to test the rows dynamically to calculate the matches and the equally ranked cells may not be next to each other you will have to use a two column solution. Otherwise you will create a circular error - ie the value of a cell (A) depends on the value of a cell (B) which is calculated using the result of the original cell (A).
So add column aa after column z and put this formula in cell aa3 and then copy it down:
=IF(COUNTIF(Y$3:Y$38,Y3)>1,"=","")
HTH
EG
Last edited by ExGrunt; 30th Mar 2012 at 09:17.