Casio

The Casio fx-991DE PLUS is a powerful scientific calculator with a natural display that makes it easy to see and understand your calculations. This calculator features a wide range of functions including: * Algebra * Calculus * Statistics * Matrix functions * Vector functions * Base conversions * Trigonometry * And much more! The fx-991DE PLUS is also equipped with a two-way power system, so you can use it even when you don't have a battery. Comes with a carrying case for convenient storage.