I thought this topic is covered somewhere, but didn't find any information on it.
I have an activity (a custom one) which the students can be submit to get a better grade. Technically the grade for the activity can be either 1 ("done") or "-" ("not done"). Now I would just like to use the "-" as 0. For example in formula: "=3 + ACTIVITY". It works for those, who have 1 for the activity. Those with empty grade ("-") get empty result ("-").
Is it possible to use empty grades in formulas somehow? How is it done correctly? Moodle version 3.2.
Thanks!