When checked causes a drop down to appear beneath it which contains a list of scored question types that you can use to force a group of scored answers to sum up to.  For example:  If you asked in an earlier question how many patients a dentist saw yesterday and the answer was 22, and then asked a question like, "and how many did you treat for"

 

Fillings

Just a check up

Clean

Other

 

then the total of these answers would need to add up to the answer given in the previious question, in this case 22.