CASIO ClassWiz FX-991CW Scientific Calculator, Black

The Casio ClassWiz FX-991CW is a scientific calculator designed for mathematical and engineering tasks. This 12-digit model handles statistical analysis, spreadsheet functions, and equation solving. Users can perform numerical integration and differentiation directly on the device. A dot-matrix display renders complex mathematical symbols clearly, and symbolic notation for fractions, pi, and square roots is available in all modes. The "Math Box" provides guided tasks for learning and practice, and the calculator supports matrix operations for linear algebra and engineering applications.

The device is powered by a single LR44 battery and features an automatic power-off function to save energy. The calculator weighs 95 g and measures 77 x 107 x 162 mm for portability. It includes a protective cover to shield the buttons from wear. An icon-based menu is used to select calculation modes. This model has a flat profile without a tilting or secondary display, designed specifically for handheld use.

• Inequality solver: finds solution sets for non-linear expressions.
• Nine memory registers: for storing and retrieving values during complex calculations.
• 24 levels of nested parentheses: enables the input of structured algebraic formulas.
• Random integer generator: for probability experiments and statistical sampling.
• Dedicated negation key: for quickly changing values to negative during input.
• Automatic fraction simplification: converts complex fractions into their simplest form.
• Angle conversion: supports switching between gradians and radians for engineering applications.
• Numeric conversion: allows for rapid switching between decimal, fraction, and percentage formats.