Casio fx-991EX ClassWiz Online Calculator

Keypad and app navigation

MENU opens Calculate, Complex, Base-N, Matrix, Vector, Statistics, Distribution, Spreadsheet, Table, Equation, Inequality and Ratio. Use the arrows and =, or click an app. OPTN offers operations for the current app. SHIFT CALC opens the numerical solver.

SHIFT activates the gold label and ALPHA activates the pink variable label. SHIFT MENU opens setup; STO stores a result, and SHIFT STO recalls a variable. M+ and SHIFT M+ add to or subtract from independent memory M.

Click the calculator to type numbers and operators. Enter calculates, Escape clears, and arrows edit an entry or navigate a menu. The Expression field accepts named functions and longer expressions. AC clears errors so you can edit. Back closes a menu or form; = calculates its fields. Additional comma and Back controls make the web interface easier to use.

Fractions, roots and display formats

For one half, enter 1, the fraction key, 2, then calculate. Right moves into a fraction’s denominator or closes its template. SHIFT fraction enters mixed(whole, numerator, denominator). A root template uses root(index, radicand), and the logarithm template uses logbase(base, value). The calculator groups implicit multiplication before explicit division, so 6÷2(1+2) evaluates as 1.

S⇔D switches Standard and Decimal output. SHIFT S⇔D requests a mixed fraction; ENG selects engineering notation. The °′″ key formats an answer as degrees, minutes and seconds, and SHIFT °′″ factors an integer. Standard output recognizes selected fractions, multiples of π and simple radicals. Decimal inputs usually start with decimal output. Recognition uses a bounded numerical search and does not perform general symbolic algebra.

Setup provides Norm 1, Norm 2, Fix 0–9 and Sci 1–10 significant digits. Norm 1 uses scientific notation below 0.01 or at 10 billion and above; Norm 2 extends the small-number threshold to 10⁻⁹. Choose Math input/Standard output for textbook display or Line input/Decimal output for linear display. Editable cursor navigation can use linear notation.

Equations, calculus and tables

Equation includes a numerical solver, polynomial equations of degree 2, 3 or 4, and simultaneous linear systems with 2, 3 or 4 unknowns. Enter coefficients in the labeled fields, then Calculate. Inequality solves real polynomial inequalities through degree four and shows intervals with open or closed endpoints. Ratio solves A/B = C/D with exactly one field entered as ?.

Catalog → Numeric calculations includes derivatives, definite integrals, finite sums and products. Derivatives use the current angle unit. Numerical solvers find a root near a guess within finite bounds; they do not list every root. Bounded algorithms report an error when they cannot establish a reliable result.

Table evaluates one function for up to 45 rows, or f and g for up to 30 rows, using inclusive start, end and step settings. CALC evaluates the entered expression with stored variable values. Use STO and ALPHA to update and insert a variable before recalculating. Native input fields and calculator keys both work in forms.

Matrices, vectors, complex and Base-N

Matrix defines MatA, MatB, MatC and MatD with dimensions up to 4×4. Enter values in row order, separated by commas. The menu provides determinant, inverse and transpose. Vector defines VctA through VctD with two or three real components and offers dot product, cross product, magnitude, unit vector and angle. MatAns and VctAns retain the latest expression result.

Choose Complex before working with i. The menu includes conjugate, real and imaginary parts, magnitude, argument and polar construction. Setup selects rectangular a+bi or polar r∠θ output. Base-N provides DEC, HEX, BIN and OCT plus logical functions. It uses signed 32-bit integers, truncates fractional computed results and displays negative nondecimal values using two’s complement. Scientific functions and fractional literals are restricted in Base-N.

Scalar memories are A, B, C, D, E, F, M, x and y. Memories and Ans survive AC and app changes. The reset menu can reset setup, clear scalar memories or initialize the whole calculator.

Statistics, probability and spreadsheet

Statistics stores data lists and computes one-variable or paired statistics with optional integer frequencies. Supported regressions are linear, quadratic, logarithmic, abˣ, aeᵇˣ, power and inverse. Data capacity is 160 rows with one populated column, 80 with two, or 53 with three. Statistical calculations enforce the corresponding number of value and frequency columns. Distribution provides normal density, cumulative area and inverse normal, plus binomial and Poisson probabilities. The menu lists argument order.

Spreadsheet provides A1:E45. Choose a cell, edit its input and Save cell. A calculation without = is evaluated once as a constant. A formula beginning with = recalculates from current variables and cells. Enter rand or randInt without = to save a random constant; each successful entry advances the shared session's seeded generator. A constant fill evaluates once and saves the same value in every filled cell. Enter Ans without = to freeze the current answer as a constant. Formulas using randomness or Ans, including through stored functions, are unsupported. Use references such as A1, absolute references such as $A$1, and range aggregates such as sum(A1:A5), min, max and mean. Spreadsheet tools fills a range, shifts relative references and preserves absolute references. Cycles, invalid references and overly long cell entries are rejected without changing saved data. ON and OFF clear the spreadsheet.

Worked examples and sharing

Choose an example to start fresh. Follow waits for the highlighted key. Play step switches to Watch, presses the remaining keys and pauses at the instruction boundary. Pause keeps progress; Show me completes the instruction immediately. Back and Restart rebuild previous steps. If you explore on your own, Return to example restores the lesson.

Copy link shares the current lesson progress or the calculation’s recorded inputs. Input lengths, memory dimensions and playback events are bounded to keep the calculator responsive. A notice appears when a session becomes too long to share. Reset calculator starts a new shareable session.

Simulator limits and reference

Menus, template editing and forms are adapted for the web. Calculations use floating-point arithmetic with up to ten displayed significant digits; rounding can differ from the handheld. Derivatives and integrals can be inaccurate at discontinuities or poorly scaled inputs. Selected constants use standard SI definitions and CODATA values; this catalog is a subset and may differ from a handheld’s historical reference values. Prime factorization is limited to integers from 2 through 10⁹.

This simulator does not reproduce Casio firmware, exact pixel layouts, automatic power down, unrestricted symbolic algebra, graph plotting or the ClassPad QR service. A shared simulator link opens LivePhysics. Use your teacher’s or exam provider’s rules when choosing a physical calculator for a test.

Model controls and capacities follow the official Casio fx-991EX ClassWiz manual. See the Casio product page and NIST constants reference for source information.

Frequently asked questions

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