LibreOffice Calc: get the distinct/unique values in a list of elements

This video demonstrates how to get the distinct/unique values in a list of elements.

Procedure to get the distinct values in a list of elements:
- Select the list of data that you want to process
- Click on the top menu 'Data'
then click on the option group 'More Filters'
and finally on the option 'Standard Filter...'
- In the new window, change the 'Field Name' on the first row to '- none -'
- Click on the 'Options' label and enable the 'No duplications' checkbox
- Finally press the 'OK' button

[meomarte]

That is cool, but how could one make a formula that would calculate the number of distinct entries without filtering?