This comprehensive guide simplifies the use of the Casio fx-991ES/PLUS/2nd Edition calculator for students, educators, and professionals, offering step-by-step instructions, real-life examples, and clear explanations. Covering topics like algebra, matrices, vectors, statistics, and more, it walks users through essential functions, modes, and settings—making it ideal for both beginners and intermediate users. Whether for exams, teaching, or self-study, this book serves as both a learning tool and a practical manual for mastering the calculator with confidence. It also helps you distinguish an original Casio calculator from the fake ones.