Scientific Calculator Casio FX-991DE X Desktop Black

The Casio FX-991DE X Desktop Black is a scientific desktop calculator designed for advanced mathematical, engineering and statistical work. It combines battery and solar dual power for reliable operation and offers a broad set of functions for algebra, calculus and statistics in a compact, black housing intended for desktop use. The calculator supports precise numeric entry, multi-line display viewing and a menu structure adapted for academic and professional tasks.

Advantages

The device provides dual power (battery and solar) to reduce unexpected shutdowns and prolong service life. Its function set covers a wide range of calculations including algebraic expressions, derivatives, integrals and statistical analysis, enabling complex problem solving without external software. The desktop form factor gives a stable working surface and a clear, easy-to-read display layout for continuous use.

Suitable for

• High school and university mathematics and physics exercises
• Engineering calculations and technical studies
• Statistical analysis and data processing tasks
• Classroom use, exam preparation and desktop reference

Key specifications

• Power: dual power source (battery and solar)
• Functions: algebra, calculus (derivatives and integrals), statistics, fractions and complex numbers
• Display: multi-line display for expression entry and result review
• Form factor: desktop model with stable base and full-size keys
• Design: black casing suitable for professional environments

How to use

Place the calculator on a stable, well-lit desktop surface. Power is managed automatically between solar input and battery; ensure the solar panel receives sufficient light for optimal operation. Enter expressions using the multi-line display to review complex formulas before confirming calculations. Use the mode and function keys to switch between calculation types (e.g., algebraic, calculus, statistical) and follow on-screen prompts for parameter input. For series of calculations, clear the entry or use the memory functions as appropriate.

Usage recommendations

Keep the calculator in moderate lighting to maintain solar charging and replace the battery according to the manufacturer’s guidance if power becomes unreliable. For exam or classroom use, verify allowed device models with the institution. Clean the keys and casing with a soft, dry cloth and avoid exposure to excessive heat or moisture to preserve functionality.