I have a question regarding the computation rules for a text field. It is a Group-X with a Select Simple field that has values to select from 0-9. I now want to add up all the values in this group and output them as a total in a simple text field. If I insert a calculation rule with Sum+ in the text field and select the above Select Simple field as the field, then for each of the different values of this Group-X (1-20 instances possible) the value is delivered to me as it was selected in the Select Simple field. However, I need the total of all possible fields of this group.

Can someone please help me, to find out what I need to enter in Computation -> Custom as a formula to get the total of all possible options (1-20 different fields are allowed). Would be very happy if someone here could help me with the formula. Thank you in advance!