How do I count the number of selected tick boxes on a CRM form?

How do I count the number of selected tick boxes on a CRM form?

Hello all

I have eight tick boxes (custom fields) on my CRM form. How can I create a formula the counts how many of them have been ticked? I can't create a formula that uses existing custom fields, so I can't create a field for each tick box that holds a numerical value and then add them together. The lack of options for custom fields and associated formulae makes them of limited use.

Any advice would be gratefully received.