I have a list of number with many duplicates. I need to know how many unique
numbers are in that list. For example if the list was 2,2,2,3,4,5,5,5,6 I
would like to know that there are 5 unique numbers in the list.

This spreadsheet will be updated by people who are not familiar with Excel,
so I would like this to be as automated as possible.

Thanks