a) None of this add up
b) None of this adds up
I think (b) is correct ..Am I right?
That's a quite interesting question.
To me, 'none of this adds up' is grammatical, but doesn't make much sense, because 'none' might give the idea that there's more than one item among a few/many:
None of these work.
No one of these work.
No one of this adds up.
Unless of course, the context is different:
None of this [kind of product] works.
I don't think it's possible to win an argument by asserting that 'none' is either singular or plural.
Here are more opinions:
Is it none of them works or none of them work? - Yahoo! Answers
Singular/plural - none - WordReference Forums