CheckBox and Calculations

I have a survey that I want to circulate using pdf and I'm a real beginner...zero experience!

A series of questions should be responded to on a Likert scale (1-4), each question would therefore have a score of 1,2,3 or 4.

The Sub-Score of each question should contribute to a Total Score.

For example:

Question 1: Text aaaaaa      1     2     3   4     Sub-Score=4

Question 2: Text bbbbb      1     2    3   4     Sub-Score=3

Question 3: Text ccccc      1    2     3     4     Sub-Score=2

                                                                  Total Score: 9

I have started with:

event.value = getField("CheckBox1").value === "Off" ? "" : 1

This allows a check box to be selected and a sub score of 1 to be returned!

It doesnt allow for possible scores of 2,3 or 4.

Please help

Regards

Chris