Countif/ifs formula but not counting duplicates

Hi,

I have an excel table that looks as follow:

Month Delivery no.
1 011
1 011
1 013
1 014
3 015
3 015
3 016
4 017

I need to be able to count the number of unique deliveries in any given month. For example, for month number 1 there are 3 deliveries. I used the formula sumproduct(1/(countif). This works well for the all months, I am not sure I to finish off the formula by wanting to do the same but just for month number one

Any helps would be great

Thanks

Vito11

Hi,

Thanks for your help and for sending the web link in which I was able to find the formula I need although I could not make it work:

{=SUM(--(FREQUENCY(IF(A3:A12="1",B3:B12),B3:B12)>0))}


Month Delivery no.
1 011
1 011
1 013
1 014
3 015
3 015
3 016
4 017

Ps - can't use pivot as my team member not very familiar with it

Any helps would be great

Cheers

V

Thanks ever so much!