I'm not sure if I'm right, but it seems to me you are trying to do mathemetics while setting the string.
I would choose to seperate numbers from strings and first perform the mathematics and use the the string to display the result.
This would also give you better control over the numbers if you were to change them.
something like:
Add a new objectvariable and call it Totalpoints
if x2 set totalpoints to 2*points
if totalpoints is not 0 use it in the string