Pull down menu and calculation

I am creating a workshee that has a pull down menu. What I would like to do is when a use selects the pulldown menu a score appears in the adjacent
cell. For example if I have a text criteria "Participates not at all" set to 0 and so on...if the user selects this option then 0 should appear in the next cell. In the end I would like to have five categories with 4 grade options to create a grade total. I hope this makes sense so someone. Please help.