So, in a tournament, there are several events. Each event has so many people sign up for it. There is a total number of people attending the tournament, and each person can sign up for multiple events.
If Joe signs up for 2 events, and Mary signs up for 3, John signs up for 1...
There are 3 people/registrants, but 6 somethings. (2 + 3 + 1)
What is that somethings? (Does it even exist?)
Edit:
"Entries" just occurred to me as a possible answer. I've been thinking about this all night and wonder what else is out there.
