Adding to a score issue - SOLVED!

Likely my incompetence not a bug but here goes …
I have a quiz skill that adds to the users points score if they get the question correct.
So I use the SET block …
If the number of points per question is fixed I can put
SET {currQuizScore} TO:
( {currQuizScore} + 2 )
…and that works fine. The score accumulate correctly - 2, 4, 6 etc

However the points for the correct answer are held in the Quiz Manager Google Sheet so that they can be changed. So I pull the value through by mapping it to a variable, and hence my SET block now looks like this:
SET {currQuizScore} TO:
{ {currQuizScore} + {questionPoints} )

But now the addition to the score does not work - the scoring goes 2, then 22 !
The second SET block is concatenating the values rather than adding them together.
Is there a way I can get VF to add the two variables as numbers ?

I found a way to solve this … which is to create 2 VF variables and use a CODE block to transform the mapped variables to numeric as follows:

var Num1 = parseInt(currQuizScore, 10);
var Num2 = parseInt(questionPoints, 10);

I can now use the SET block to add Num1 and Num2 - job done !