Non-Programmable Scientific Calculator with 417 Functions With Natural Textbook Display so your functions and equations look same as in your textbook List Based Stat-Data Editor for Easy Viewing and Statistical Calculation Probability, Calculus, Permutation Combination, Random Number Calculation features Table Function for Function exploration Colour coded keypad for easy key differentiation for Secondary and tertiary functions. Dual Powered - Solar & Battery so that you can use for long time without the need of battery replacement Comes with slide-on hard case Recommended by Engineering & UG Maths Students fx-991ES Plus is non-programmable Scientific Calculator with 417 functions. It has Natural Textbook Display so that you can type and see algebraic functions the way it is written in your books. Calculator has dual power source: Battery & Solar. It can solve advance functions like Integration, Differentiation, Matrix, Vector, Polynomial, Simultaneous Equations etc.