In say cell C1 type in:
=SUM(1/COUNTIF(A1:A10,A1:A10)) <<Do Not Press Enter As Usual; Instead
Press (the 3 keys simultaneously) Ctrl + Shift + Enter -- This should
"Add" internally two { } characters - ONe at the beginng and one at the end
These {} can not be entered at the keyboard.

HTH



"BigMac" wrote:

Hi there,

I'm wondering how I'd be able to have a formula to calculate the number
of cells in a row which have appeared once and even though the value
appears many times in that row, I'd only count it as once. For
instance:

A
----
M
M
N
E
F
G
T
S
T
S

The result I'd want is 7, not taking into consideration the repeated
alphabets M, T and S. I wish to only count each alphabet once, not
matter whether if they are repeated or not.

Thanks!