Why iViX is 15 and not 5?


“i” here is any non-roman String,
So we are to ignore the same & thus our actual roman literal is: VX,
So shouldn’t the answer of same be 5 instead of 15?

or are we still considering the non-roman numerals as some padded literals i.e. those helping in separating the roman numerals with each other? That’s just my assumption.
Seeking for the correct explanation.