Christophe, as I see from what I can found: https://hal.archives-ouvertes.fr/hal-01061671/document
We have for some question some coefficient (.567) and 5 answers.
Current workaround before new feature will be available
To avoid division later you can multiple before.
So instead of setting in scores values like 1,2,3,4,5 you can set there premultiplied values like 1*.567,2*.567,3*.567,4*.567,5*.567 which will be 0.567, 1.134, 1.701, 2.268 and 2.835 respectfully.
But I’m nor completely understand the model of those test still. Anyway I think we should add those Math operators.