I brought two. The old and trusty TI 30X II S I used for all 9 CAS exams and the new TI-30XS Multiview, which I now prefer. Careful you don't use the TI-36X (which in Europe used to be called the 30XS Professional) as that is not allowed.
Make sure you check the latest rules on calculators published on the Profession's website http://www.actuaries.org.uk/news/articles/hp12c-calculator-now-reinstated-exams
