Do you get a blank paper at SAT exam?

For some maths calculations.

You can write in the test booklet.

Nope, you do your work in the booklet. You could ask your proctor if you could use a seperate sheet of paper but a strict proctor may say no.

^I don’t think proctors are allowed to give extra scratch paper, in order to preserve fairness between test-takers.

And is there enough space in the booklet?

@barborazel There is more than plenty of space in the booklet. Do not worry about space on the test.