Feature: 1. Comprehensive Functionality: The TY-991ES scientific calculator boasts 417 built-in functions, including trigonometric, exponential, logarithmic, calculus, statistics, algebra, and more. It also supports complex number, matrix, and vector calculations, catering to a wide range of scientific and engineering needs. 2. High-Definition Display: Featuring a high-definition dot matrix display (96*31), this calculator ensures clear and easy reading. It supports natural display, allowing for the direct input and output of mathematical formulas, making complex calculations more intuitive. 3. Dual Power Source: Equipped with a solar panel and a button battery, this calculator offers continuous operation in both indoor and outdoor environments. This dual power source design reduces the need for frequent battery replacements, making it an economical choice for long-term use. 4. User-Friendly Design: The TY-991ES calculator features large, clear numeric keys and a protective cover with an anti-collision design. This thoughtful design ensures durability and ease of use, making it a reliable tool for frequent calculations. 5. Versatile Use: Ideal for students, teachers, engineers, accountants, and more, this calculator can meet various calculation needs in mathematics, science, and engineering. Its compact size and comprehensive functionality make it a great gift for those in need of a scientific calculator. Specification: Model: TY -991ES Color: White, Black, Pink, Blue (Optional) Size: 165x80x15mm Weight: 125g Battery: LR44, 160MaH 1.5V Material: ABS Platsic Package List: 1 x Calculator