The numbers in this problem may contain letters as well as numbers.

I have a lot of invoice numbers that I need to count. Some are
associated with a Purchase order number (in some cases multiple
occurances of the same invoice number are associated with one purchase
order and sometimes it is different invoices associated with a
purchase order number.)

First, I need to count the number of unique PO nos. for those where a
PO number shows up. Then, I need to count the unique invoice numbers
without a PO number.

I was using the following array formula:
=SUM(IF(FREQUENCY(IF(LEN(E2:E148)0,MATCH(E2:E148, E2:E148,0),""), IF
(LEN(E2:E148)0,MATCH(E2:E148,E2:E148,0),""))0,1) )

But it doesn't seem to be producing the right results. Here is an
example of my numbers
Invoice no. PO Number
40701429 763334
40701429
40701429
40701431 768346
40701431
40701525 763334
40701525 763334
40701525
40701525
40701592 748407
40701592
40701393


5 invoice numbers 4 po's in the list above is what the answer should
be in this short example. How is the best way to get accurate results
with many numbers? Thanks!