Does this look right?


If so, it's a Rollup field with the formula `SUM(values)`
Link to base
Hello Marine,
You can do that by adding a rollup field in your Events table.
First step, if not done yet, is to link "Attendees" table to Events Table:

Field "Events" is a linked field to table Events:

You then add a rollup field in table Events:

To get the following result:

Regards,
Pascal
Sorry,
I started writting my answer before Adam posted his answer.
Do not consider my answer.
Regards,
Pascal
Sorry,
I started writting my answer before Adam posted his answer.
Do not consider my answer.
Regards,
Pascal
@MarineSoratoAh, please consider Pascal's answer; his is clearer than mine and includes a step by step process of how to create the rollup field
@Pascal_Gallais-Hahaha I've done this a couple of times too, sorry about that!