If ur area does not contain blank cells, the following should work:
=SUM(1/COUNTIF(A1:A10,A1:A10)) press ctrl+shift+enter as this is array formula

HTH


"auyantepui" wrote:

how can I count equal numbers in colum A as unique ones? for example:

Regardless there are 3 (6452301) i need to count them as one Sales Order and
not as three, as so on:

6452302
6452301
6452301
6452301
6452303
6452303
6452303