I see 1 issues with 1 bug.
It’s adding a number to a string which is basically adding 2 strings so it appends the 2 values instead of mathmatically adding them.
You can move the parenthesis ToString(roundTo(Variable(Totalscore),9) + score)
That still doesn’t convert a large number to a string. For that you need LargeNumberToString() instead of ToString() unfortunately, LargeNumberToString() seems broken,