from (distant) memory, pen and paper provided, none of the arithmetic needed a calculator. For the interrupt test, it really helps to write down all your workings for the arithmetic questions so you can get back to them. And accuracy scored better than number of questions answered - don't rush and make mistakes. If you forget the interrupt question, just ignore it and continue with the arithmetic. Good luck - come back and let us know how you go, either way, and any advice for future applicants.