*CASIO fx-991EX*

## Features

### Intuitive, easy-to-learn icon display

The use of icons on the menu screen improves viewability.
Selection of the desired function is quick and easy.

### Natural Textbook Display

Input and display fractions, powers, logarithms, roots, and
other mathematical formulas and symbols just as they appear in textbooks.

### List display function for thorough, speedy learning

Variables and statistical calculation results stored in
memory can be displayed in lists. There’s no need to recall and confirm
individual values as with previous models.

### Easy-to-understand English messages and interactive format

Nearly all English words are displayed on the screen in
unabbreviated form. Interactive menu display realizes more intuitive operation.

### High computational competence for performing even advanced mathematics

ClassWiz contains calculation functions that support even
advanced mathematical operations, including spreadsheet calculations, 4 × 4
matrix calculations, calculation of simultaneous equations with four unknowns
and quartic equations, and advanced statistical distribution calculations.

### Online Visualization Service Using QR Code

Generate QR codes of equations input into the calculator by
a simple operation. Graphs and other graphics can be displayed on smartphone or
tablet screens.

### A comprehensive set of advanced functions unique to CASIO scientific
calculators

### Spreadsheet calculations

Useful for learning statistics. Up to 5 columns × 45 rows
(maximum of 170 data items)

### Matrix calculations

Perform calculations with matrices of up to 4 rows and 4
columns.

### Vector calculations

Perform calculations using up to four third-order vectors
stored in memory.

### Multiline display

Formulas are automatically wrapped to multiple lines. *

*In linear input mode

### Integration calculations

Perform integration calculations in advanced mathematics.

### Differential calculations

Perform differential calculations in advanced mathematics.

### Equation calculations

Calculation of simultaneous equations in 2 to 4 unknowns and
high-degree equations of second to fourth degree

### Inequality calculations

Solve second-degree to fourth-degree inequalities.

### Advanced statistical distribution calculations

Perform calculations involving normal distributions,
binomial distributions, and Poisson distributions.

### Ratio calculations

Perform ratio calculations such as A:B=X:D.

### Metric conversions

Select units from the Metric Conversion Command List.

### Scientific constants

Select scientific constants from the Scientific Constant
Table.

### Variables list

One-touch list display

### Statistics list

Displays six rows at once.

### Digit separator

Separation every three digits makes even large numbers easy
to read.

### Engineering symbols

Perform engineering calculations that include symbols such
as k, M, m, and n.

## Specifications

Dot matrix display

High-resolution screen provides beautiful
looking graphs every time.

**Multi-replay**

Quick and easy recall of previously executed
formulas for editing and re-execution.

**Plastic keys** Designed and engineered for easy operation.

**List based STAT-data editor** Viewing and editing of input
data in list format, showing data groups (x-data, y-data, frequency) and
surrounding data.

**Natural textbook display**

Display expression same as
textbook.

10 + 2 digits 10-digit
mantissa + 2-digit exponential display.