Model# 2162466 - HWP-40GS (F2225AA#ABA) HP 40gs Graphing Calculator for Math - Science - Engineering, 600 Functions/Easy programming to create custom aplets using formulas and equations/ Interactive history, notes and sketch capabilities / USB and has been specifically designed with both students and teachers in mind. As your calculations become more and more intricate, the HP 40gs makes solving them easy with a built-in Computer Algebra System (CAS). CAS delivers dynamic symbolic manipulation and numeric solving so you can easily perform complex arithmetric or calculus functions.