How to total all numbers that the user inputs

Question

As you can see, I've put a question mark in where I assume the code should be added that totals all the numbers that user inputs.
Would appreciate either an answer or help.
Many thanks!
https://code.sololearn.com/WEQC9B3JPKCK/?ref=app

Answer 1

This is similar.

https://code.sololearn.com/Wz8vP7bG95nP/#js

Answer 2

All good. Figured it out. Was something simple