Some good math calculators are the TI-Nspire CX Cas, TI-84 Plus C Silver Edition, Casio Prizm, HP Prime and TI-89 Titanium. These calculators are capable of handling basic arithmetic, complex scientific formulas and graphing.
The TI-84 Plus C Silver Edition is an updated version of the popular TI-84 Plus with a full color screen, high resolution, back light and rechargeable battery. The TI-84 Plus C Silver Edition is useful for high school students because it is permitted in all standardized high school tests including the SAT, PSAT and ACT. The TI-89 Titanium is a college-level calculator perfect for calculus and other advanced math. As of June 2015, it is not allowed for the high school ACT and International Baccalaureate tests.
The TI-Nspire CX Cas is considered to be the most advanced calculator on the market, as of June 2015. It features full color, drop-down menus, files and folders, high-end graphing capabilities and a simple user interface.
The Casio Prizm model is regarded as one of the easiest calculators to get used to. The Prizm also has a full-color screen with advanced graphing capabilities. The TI-Nspire and Casio Prizm have a disadvantage in that their use is restricted on a few standard exams. The HP Prime calculator has unique touch screen functionality and is legal to use on most standardized tests for high school students.