The easiest way to find the number of active adults in your system is to run an advanced search. This will allow you to sort through your system and find the people that aren’t active, and properly have them marked as Contacts or Archived.
Begin by navigating to People > Advanced Search.
From here, set your filters to ‘Family Relationship’ ‘does Not Contain’ ‘Child’, and ‘Contact’ ‘Exclude contacts’, as shown in this image.
This will bring up a list of people considered ‘Active Adults’ within the account.