I used the scrap paper for the maths questions and I still passed. I'm a visual thinker, in that sometimes I have to write something down, maybe in a different way to be able to solve it. It may even be a way to calm the nerves.
I answered all the other questions and came back to the maths ones. That way I could take more time, work them through correctly and thoroughly and not have any remaining questions nagging at me and panicking me.