Try this:

=SUMPRODUCT((A1:A50<"")/COUNTIF(A1:A50,A1:A50&""))

This should work even though you might have blank cells in the range.
--
HTH,

RD
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Please keep all correspondence within the Group, so all may benefit!
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"Watercolor artist" wrote in
message ...
I need a formula that will count all the different instances of a value in
a
column. For example, in the example below, the count would be 3 because,
"1,"
though it occurs thrice, will only be counted once.

Col A
1
1
2
3
1

Thanks in advance,
Howard