Err:502; how to repair?

Where can I get info?
Trying to MULT 15 aec. * 10.
Using =sum(((0:15)*0) ?

Every open bracket should have a closed one.

https://wiki.documentfoundation.org/Faq/Calc/015

Duplicate of Where is info on Err: 102? where the cause and solution is given in answer.

Have you read these answers?

And you can read this side.