Scientific Calculator fx-991EX

Scientific Calculator fx-991EX is an academic-level scientific calculator that solves mathematical expressions in natural textbook format — fractions with horizontal bars, square roots with radical signs, and powers with superscripts, rendered exactly as they appear in your textbook.

Built for university students, engineers, researchers, and professionals who need precision and clarity in every calculation.

NATURAL TEXTBOOK DISPLAY
Enter and view expressions in two-dimensional textbook notation. Fractions, radicals, and exponents are displayed in their true mathematical form — not as flat text. Switch between Natural Display (MathIO) and Linear Display (LineIO) anytime.

EXACT FORM RESULTS
Get results as simplified fractions, square roots, and π expressions — not just decimals. Toggle between exact and decimal forms instantly with S⟷D. The calculator automatically detects when a result can be expressed exactly.

COMPLETE TRIGONOMETRY
All standard and inverse trigonometric functions: sin, cos, tan, sin⁻¹, cos⁻¹, tan⁻¹. Three angle modes: Degrees, Radians, and Gradians. Near-zero results are snapped to exact zero to eliminate floating-point artifacts.

FULL COMPLEX NUMBER SUPPORT
Enter and compute with complex numbers in rectangular (a+bi) or polar (r∠θ) form. Access conjugate, magnitude, argument, real part, and imaginary part functions. Convert between rectangular and polar coordinates with Pol and Rec.

FRACTIONS & MIXED NUMBERS
Work with improper fractions and mixed numbers. Results are automatically reduced. Switch between mixed fraction (a b/c) and improper fraction (d/c) display with one tap.

POWER & ROOT FUNCTIONS
Square, cube root, nth root, arbitrary powers, reciprocal, 10^x, and e^x — all rendered in proper mathematical notation with two-dimensional templates.

LOGARITHMS
Base-10 logarithm (log) and natural logarithm (ln) with full precision.

40 SCIENTIFIC CONSTANTS
Instantly access 40 fundamental physical constants organized in 5 groups: particle masses, quantum mechanics, electromagnetic, thermodynamic, and universal constants. Constants are displayed with their standard symbols.

ADVANCED MATH FUNCTIONS
• Factorial (x!) for integers 0–69
• Permutation (nPr) and Combination (nCr)
• Absolute value, integer part, fractional part, floor
• Random number (Ran#) and random integer (RanInt#)
• Percentage calculations

MEMORY & VARIABLES
Store and recall values in 26 named variables (A–Z) plus an independent memory register (M) with M+ and M− operations. The last result is always available via Ans.

CALCULATION HISTORY
Browse up to 30 previous calculations. Scroll through history with arrow keys and replay any past expression for quick editing and recalculation.

DISPLAY FORMATS
• Norm — Standard notation with automatic scientific switching
• Fix — Fixed decimal places (0–9 digits)
• Sci — Scientific notation with configurable significant digits
• 15-digit internal precision, 10+2 digit display

PROFESSIONAL PRECISION
15-digit internal calculation precision. Numeric range from ±1×10⁻⁹⁹ to ±9.999999999×10⁹⁹. Automatic parenthesis closing. Multi-statement evaluation with colon separator. Full error handling with edit-mode recovery.

DESIGNED FOR EDUCATION & ENGINEERING
Whether you are solving homework problems, preparing for exams, or performing professional engineering calculations — Scientific Calculator Emulator gives you the accuracy and clarity of a dedicated hardware calculator on your iPhone.