For "cell number" try (with array A1:C3 and E2 as lookup):

=MATCH(2,1/FREQUENCY(E2,A1:C3*1))

"Geoff Lambert" wrote:

In Excel2003 is it possible to use something MATCH() on a 2D array, to
find the position of a particular entry? The result could be expressed
as a 2-element vector of {row,column} or as a single number
representing the "cell number" (e.g. in a 3x3 array, the middle cell
would be #5

Geoff Lambert