count a group of numbers but do not count duplicates

[Lisaml]

I need to count a column of numbers but do not want to count the duplicate
numbers. How do I do this?

 

[Myrna Larson]

I'm not sure whether you want to count the number of unique entries or to sum
them. Assuming it's the former:

=SUM(1/COUNTIF(A1:A20,A1:A20))

entered as an array formula with CTRL+SHIFT+ENTER

If you want to sum the first occurrence of each unique number, use a "helper"
column (say C) with this formula, copied down as far as needed.

=COUNTIF($A$1:A1,A1)

Then use =SUMIF(C1:C20,1,A1:A20)

 

[Ola]

Try this: http://www.cpearson.com/excel/duplicat.htm
Look under "Counting Unique Entries In A Range"

Ola Sandstrom