Excel: How do I get a dynamic formula which can display a total of unique values in a range?

Question

Example range:

A10=100, 
A11=105, 
A12=100, 
A13=100, 
A14=7, 
A15=105.  

The formula I need would display "3" only as there are only 3 unique values in this set. The spreadsheet will be updated to add more values as needed in the column "A". Blanks should not be included in any total.

Answer 1

From here:

=SUM(IF(FREQUENCY(A10:A1000,A10:A1000)>0,1))