Yes, you can use a calculator for math-related questions. But don’t expect to be able to pull out your smartphone and use the calculator on it. You will have to have a separate calculator that is battery-operated and makes no noise. Calculators with simple memory are acceptable. However, programmable calculators and graphing calculators are forbidden.  A good option is the Casio FX-115 ES Plus. To be sure, check with your testing facility before the test day or refer to your exam candidate booklet about what type of calculator is allowed on the exam. If you plan to work for a sponsoring broker once you pass your exam, you may also ask someone at your home location which calculator is best for the exam.