A full-featured browser emulator of the Casio fx-991ES PLUS — the world's most popular scientific calculator. Supports 403 functions across 10 calculation modes including integration, differentiation, matrix operations, statistics, complex numbers, and equation solving. No download, no sign-up, works offline.
Compute definite integrals numerically. Enter ∫(f(x), a, b) — supports polynomial, trigonometric, exponential, and logarithmic integrands.
Numerical differentiation at any point. Use d/dx(f(x), a) to find the derivative of any expression instantly.
Evaluate finite sums with Σ(f(x), start, end). Useful for series, sequences, and discrete mathematics.
Add, subtract, multiply matrices up to 3×3. Compute determinant, inverse, and transpose with a few button presses.
Arithmetic in rectangular a+bi and polar r∠θ form. Includes modulus, argument, and conjugate.
Solve quadratic, cubic, and simultaneous linear equations (2–3 unknowns). Get all real and complex roots instantly.
Convert between binary, octal, decimal, and hexadecimal. Bitwise AND, OR, XOR, XNOR, NOT supported.
Mean, standard deviation, variance, and 7 regression types: linear, quadratic, logarithmic, exponential, power, and inverse.
Enter and simplify fractions and mixed numbers. Toggle between exact fraction and decimal display with S⇔D.
Frequently Asked Questions
∫( then your function, a comma, the lower limit, a comma, and the upper limit. Example: ∫(x², 0, 3) returns 9. Supports any expression math.js can evaluate.d/dx(f(x), a) to compute the numerical derivative at point a. Example: d/dx(x³, 2) returns 12. Works for trigonometric, exponential, logarithmic, and polynomial functions.= to get both roots — real or complex.3+4i (rectangular) or 5∠53.13 (polar). The calculator returns the result in whichever form you choose and supports modulus, argument, and conjugate operations.det), inverse, and transpose operations.Enter computes the result, Backspace deletes, Escape clears, arrow keys move the cursor, and ↑ ↓ scroll through expression history. ^ for powers, % for percent, ! for factorial.