Count unique value in series of data

[jusho]

Hello guys, i have a question. I need to count unique value in series of data.

Example in column B i have :
123
234
123
234
234

So i need a way to make the formula count result is 2. Because its contain only 123 and 234 but it duplicates.
How can i make that? if i use =count its result 5. I have you count until 1 million raw per day, its confused me

Thanks in advance.

 

[Andrew Poulsom]

Try eg:

=SUMPRODUCT(1/COUNTIF(A1:A5,A1:A5))