The Casio fx-991ES is a versatile scientific calculator designed for advanced mathematical calculations. It features a natural textbook display, allowing users to view expressions and results as they appear in textbooks. With over 240 functions, including statistics, calculus, and matrix operations, it is ideal for students and professionals alike. Its solar and battery power ensures reliability in various settings, and it includes a multi-replay function for efficient problem-solving. The fx-991ES is compact and user-friendly, making it a popular choice for exams and coursework