Cori,
Do not bring a calculator to your exam. You will not be allowed to take it in.
But... The PMP Exam is a computer-based exam and a "windows style" calculator is available right on the computer. So for any calculations that you need to make, simply start up the calculator on the exam computer screen.
In fact... I recommend that you start up the calculator for anything that you need to calculate. 1+1? Use the calculator. 100/2? Use the calculator!