Casio fx-991ES PLUS User manual

E
fx-570ES PLUS
fx-991ES PLUS
User’s Guide
CASIO Worldwide Education Website
http://edu.casio.com
CASIO EDUCATIONAL FORUM
http://edu.casio.com/forum/

Contents
Important Information ............................................................. 2
Sample Operations.................................................................. 2
Initializing the Calculator........................................................ 2
Safety Precautions .................................................................. 2
Handling Precautions.............................................................. 2
Removing the Hard Case ........................................................ 3
Turning Power On and Off ...................................................... 3
Adjusting Display Contrast .................................................... 3
Key Markings ........................................................................... 3
Reading the Display ................................................................ 4
Using Menus ............................................................................ 5
Specifying the Calculation Mode ........................................... 5
Configuring the Calculator Setup .......................................... 5
Inputting Expressions and Values ......................................... 7
Toggling Calculation Results ................................................. 9
Basic Calculations ................................................................ 10
Function Calculations ........................................................... 13
Complex Number Calculations (CMPLX) ............................ 18
Using CALC............................................................................ 19
Using SOLVE.......................................................................... 20
Statistical Calculations (STAT) ............................................. 22
Base-nCalculations (BASE-N) ............................................. 26
Equation Calculations (EQN) ............................................... 28
Matrix Calculations (MATRIX)............................................... 29
Creating a Number Table from a Function (TABLE) ........... 32
Vector Calculations (VECTOR)............................................. 33
Scientific Constants .............................................................. 35
Metric Conversion ................................................................. 37
Calculation Ranges, Number of Digits,
and Precision ......................................................................... 38
Errors...................................................................................... 40
Before Assuming Malfunction of the Calculator... ............. 41
Replacing the Battery............................................................ 42
Specifications ........................................................................ 42
Frequently Asked Questions................................................ 43
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Important Information
• The displays and illustrations (such as key markings) shown in this User’s
Guide are for illustrative purposes only, and may differ somewhat from the
actual items they represent.
• The contents of this manual are subject to change without notice.
• In no event shall CASIO Computer Co., Ltd. be liable to anyone for special,
collateral, incidental, or consequential damages in connection with or
arising out of the purchase or use of this product and items that come with
it. Moreover, CASIO Computer Co., Ltd. shall not be liable for any claim of
any kind whatsoever by any other party arising out of the use of this product
and the items that come with it.
• Be sure to keep all user documentation handy for future reference.
Sample Operations
Sample operations in this manual are indicated by a icon. Unless
specifically stated, all sample operations assume that the calculator is in its
initial default setup. Use the procedure under “Initializing the Calculator” to
return the calculator to its initial default setup.
For information about the , 1, B, and *marks that are shown
in the sample operations, see “Configuring the Calculator Setup”.
Initializing the Calculator
Perform the following procedure when you want to initialize the calculator and
return the calculation mode and setup to their initial default settings. Note that
this operation also clears all data currently in calculator memory.
(CLR)(All)(Yes)
Safety Precautions
Battery
• Keep batteries out of the reach of small children.
• Use only the type of battery specified for this calculator in this manual.
Handling Precautions
• Even if the calculator is operating normally, replace the battery at least
once every three years (LR44 (GPA76)) or two years (R03 (UM-4)).
A dead battery can leak, causing damage to and malfunction of the
calculator. Never leave a dead battery in the calculator. Do not try using
the calculator while the battery is completely dead (fx-991ES PLUS).
• The battery that comes with the calculator discharges slightly during
shipment and storage. Because of this, it may require replacement
sooner than the normal expected battery life.
• Do not use an oxyride battery* or any other type of nickel-based
primary battery with this product. Incompatibility between such
batteries and product specifications can result in shorter battery life
and product malfunction.
• Avoid use and storage of the calculator in areas subjected to
temperature extremes, and large amounts of humidity and dust.
• Do not subject the calculator to excessive impact, pressure, or
bending.

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• Never try to take the calculator apart.
• Use a soft, dry cloth to clean the exterior of the calculator.
• Whenever discarding the calculator or batteries, be sure to do so in
accordance with the laws and regulations in your particular area.
* Company and product names used in this manual may be registered
trademarks or trademarks of their respective owners.
Removing the Hard Case
Before using the calculator, slide its hard
case downwards to remove it, and then affix
the hard case to the back of the calculator as
shown in the illustration nearby.
Turning Power On and Off
Press to turn on the calculator.
Press (OFF) to turn off the calculator.
Auto Power Off
Your calculator will turn off automatically if you do not perform any operation
for about 10 minutes. If this happens, press the key to turn the calculator
back on.
Adjusting Display Contrast
Display the CONTRAST screen by performing the following key operation:
(SETUP)A(;CONT). Next, use Band Cto adjust
contrast. After the setting is the way you want, press .
Important: If adjusting display contrast does not improve display readability,
it probably means that battery power is low. Replace the battery.
Key Markings
Pressing the or key followed by a second
key performs the alternate function of the second key.
The alternate function is indicated by the text printed
above the key.
The following shows what the different colors of the
alternate function key text mean.
If key marking text
is this color: It means this:
Yellow Press and then the key to access the
applicable function.
Red Press and then the key to input the
applicable variable, constant, or symbol.
Purple (or enclosed
in purple brackets) Enter the CMPLX Mode to access the function.
Green (or enclosed in
green brackets) Enter the BASE-N Mode to access the function.
sin–1 D
s
Alternate function
Keycap function
sin–1 D
s
Alternate function
Keycap function

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Reading the Display
The display of the calculator shows expressions you input, calculation results,
and various indicators.
Input expression Indicators
Calculation result
• If a indicator appears on the right side of the calculation result, it means
the displayed calculation result continues to the right. Use Cand Bto
scroll the calculation result display.
• If a Eindicator appears on the right side of the input expression, it means
the displayed calculation continues to the right. Use Cand Bto scroll the
input expression display. Note that if you want to scroll the input expression
while both the and Eindicators are displayed, you will need to press 
first and then use Cand Bto scroll.
Display indicators
This
indicator: Means this:
S
The keypad has been shifted by pressing the key. The
keypad will unshift and this indicator will disappear when
you press a key.
AThe alpha input mode has been entered by pressing the
key. The alpha input mode will be exited and this
indicator will disappear when you press a key.
MThere is a value stored in independent memory.
STO
The calculator is standing by for input of a variable name to
assign a value to the variable. This indicator appears after
you press =(STO).
RCL
The calculator is standing by for input of a variable name to
recall the variable’s value. This indicator appears after you
press =.
STAT The calculator is in the STAT Mode.
CMPLX The calculator is in the CMPLX Mode.
MAT The calculator is in the MATRIX Mode.
VCT The calculator is in the VECTOR Mode.
The default angle unit is degrees.
The default angle unit is radians.
The default angle unit is grads.
FIX A fixed number of decimal places is in effect.
SCI A fixed number of significant digits is in effect.
Math Natural Display is selected as the display format.
>
Calculation history memory data is available and can be
replayed, or there is more data above/below the current
screen.
Math Math Math Math

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Disp The display currently shows an intermediate result of a
multi-statement calculation.
Important: For some type of calculation that takes a long time to execute,
the display may show only the above indicators (without any value) while it
performs the calculation internally.
Using Menus
Some of the calculator’s operations are performed using menus. Pressing
or @, for example, will display a menu of applicable functions.
The following are the operations you should use to navigate between
menus.
• You can select a menu item by pressing the number key that corresponds
to the number to its left on the menu screen.
• The indicator in the upper right corner of a menu means there is another
menu below the current one. The >indicator means another menu above.
Use Aand Dto switch between menus.
• To close a menu without selecting anything, press .
Specifying the Calculation Mode
When you want to perform this type of
operation:
Perform this key
operation:
General calculations (COMP)
Complex number calculations (CMPLX)
Statistical and regression calculations (STAT)
Calculations involving specific number
systems (binary, octal, decimal,
hexadecimal)
(BASE-N)
Equation solution (EQN)
Matrix calculations (MATRIX)
Generation of a number table based on an
expression (TABLE)
Vector calculations (VECTOR)
Note: The initial default calculation mode is the COMP Mode.
Configuring the Calculator Setup
First perform the following key operation to display the setup menu:
(SETUP). Next, use Aand Dand the number keys to configure
the settings you want.
Underlined ( ___ ) settings are initial defaults.
MthIO LineIO Specifies the display format.
Natural Display (MthIO) causes fractions,
irrational numbers, and other expressions to be
displayed as they are written on paper.


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Linear Display (LineIO) causes fractions and
other expressions to be displayed in a single
line.
Note: • The calculator switches to Linear Display automatically whenever
you enter the STAT, BASE-N, MATRIX, or VECTOR Mode. • In this manual,
the symbol next to a sample operation indicates Natural Display, while
the 1symbol indicates Linear Display.
Deg Rad Gra Specifies degrees, radians or grads as the angle
unit for value input and calculation result display.
Note: In this manual, the Bsymbol next to a sample operation indicates
degrees, while the *symbol indicates radians.
Fix Sci Norm Specifies the number of digits for display of a
calculation result.
Fix: The value you specify (from 0 to 9) controls the number of decimal
places for displayed calculation results. Calculation results are rounded off
to the specified digit before being displayed.
Example: 1100 ÷ 7 = 14.286 (Fix 3)
14.29 (Fix 2)
Sci: The value you specify (from 1 to 10) controls the number of significant
digits for displayed calculation results. Calculation results are rounded off to
the specified digit before being displayed.
Example: 11 ÷ 7 = 1.4286 s10–1 (Sci 5)
1.429 s10–1 (Sci 4)
Norm: Selecting one of the two available settings (Norm 1, Norm 2)
determines the range in which results will be displayed in non-exponential
format. Outside the specified range, results are displayed using exponential
format.
Norm 1: 10–2 |x|, |x| >1010 Norm 2: 10–9 |x|, |x| >1010
Example: 11 ÷ 200 = 5 s10–3 (Norm 1)
0.005 (Norm 2)
Aab/c Ad/c Specifies either mixed fraction (ab/c) or improper
fraction (d/c) for display of fractions in calculation results.
ACMPLX a+bi;rθSpecifies either rectangular coordinates
(a+bi) or polar coordinates (rθ) for EQN Mode solutions.
ASTAT ON ; OFF Specifies whether or not to display a FREQ
(frequency) column in the STAT Mode Stat Editor.
ADisp Dot ; Comma Specifies whether to display a dot or
a comma for the calculation result decimal point. A dot is always displayed
during input.
Note: When dot is selected as the decimal point, the separator for multiple
results is a comma (,). When comma is selected, the separator is a
semicolon (;).
A;CONTAdjusts display contrast. See “Adjusting Display
Contrast” for details.

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Initializing Calculator Settings
Perform the following procedure to initialize the calculator, which returns the
calculation mode to COMP and returns all other settings, including setup
menu settings, to their initial defaults.
(CLR)(Setup)(Yes)
Inputting Expressions and Values
Basic Input Rules
Calculations can be input in the same form as they are written. When you
press the priority sequence of the input calculation will be evaluated
automatically and the result will appear on the display.
4 ssin30 s(30 + 10 s3) = 120
4
Q30  30 10 3 
*
1
*
2* 3
*1Input of the closing parenthesis is required for sin, sinh, and other functions
that include parentheses.
*2These multiplication symbols (s) can be omitted. A multiplication symbol
can be omitted when it occurs immediately before an opening parenthesis,
immediately before sin or other function that includes parentheses,
immediately before the Ran# (random number) function, or immediately
before a variable (A, B, C, D, E, F, M, X, Y), scientific constants, Por e.
*3The closing parenthesis immediately before the operation can be
omitted.
Input example omitting *2and *3operations in the above
example.
4
Q30  30 10 3 
Note: • If the calculation becomes longer than the screen width during
input, the screen will scroll automatically to the right and the ;indicator will
appear on the display. When this happens, you can scroll back to the left by
using Band Cto move the cursor. • When Linear Display is selected,
pressing Dwill cause the cursor to jump to the beginning of the calculation,
while Awill jump to the end. • When Natural Display is selected, pressing
Cwhile the cursor is at the end of the input calculation will cause it to jump
to the beginning, while pressing Bwhile the cursor is at the beginning will
cause it to jump to the end. • You can input up to 99 bytes for a calculation.
Each numeral, symbol, or function normally uses one byte. Some functions
require three to 13 bytes. • The cursor will change shape to Iwhen there are
10 bytes or less of allowed input remaining. If this happens, end calculation
input and then press .
Calculation Priority Sequence
The priority sequence of input calculations is evaluated in accordance with the
rules below. When the priority of two expressions is the same, the calculation
is performed from left to right.



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1st Parenthetical expressions
2nd Functions that require an argument to the right and a closing
parenthesis “)” following the argument.
3rd Functions that come after the input value (x2, x3, x–1, x!, °’ ”, °, r, g,
%, t), powers (x9), roots ()
4th Fractions
5th
Negative sign (–), base-nsymbols (d, h, b, o)
Note: When squaring a negative value (such as –2), the value
being squared must be enclosed in parentheses (2 7;
). Since x2has a higher priority than the negative sign,
inputting 2 7would result in the squaring of 2 and then
appending a negative sign to the result. Always keep the priority
sequence in mind, and enclose negative values in parentheses
when required.
6th Metric conversion commands (cmin, etc.),
STAT Mode estimated values (K, L, K1, K2)
7th Multiplication where the multiplication sign is omitted
8th Permutation (nPr), combination (nCr), complex number polar
coordinate symbol ()
9th Dot product (·)
10th Multiplication, division (s, ÷)
11th Addition, subtraction (+, –)
12th Logical AND (and)
13th Logical OR, XOR, XNOR (or, xor, xnor)
Inputting with Natural Display
Selecting Natural Display makes it possible to input and display fractions and
certain functions (log, x2, x3, x9, , , , x−1, 109, e9, °, d/dx, 3, Abs) just
as they are written in your textbook.
2 + '
2
1 + ' 2

2 2 CC 1 2 
Important: • Certain types of expressions can cause the height of a
calculation formula to be greater than one display line. The maximum
allowable height of a calculation formula is two display screens (31 dots s2).
Further input will become impossible if the height of the calculation you are
inputting exceeds the allowable limit. • Nesting of functions and parentheses
is allowed. Further input will become impossible if you nest too many functions
and/or parentheses. If this happens, divide the calculation into multiple parts
and calculate each part separately.
Note: When you press and obtain a calculation result using Natural
Display, part of the expression you input may be cut off. If you need to view
the entire input expression again, press and then use Band Cto
scroll the input expression.


E-9
Using Values and Expressions as Arguments
(Natural Display only)
A value or an expression that you have already input can be used as the
argument of a function. After you have input 7
6, for example, you can make
it the argument of , resulting in 7
6
'
.
To input 1 + 7
6and then change it to 1 + 7
6
'

1
7 6
BBBB&(INS)

As shown above, the value or expression to the right of the cursor after
&(INS) are pressed becomes the argument of the function that is
specified next. The range encompassed as the argument is everything up
to the first open parenthesis to the right, if there is one, or everything up to
the first function to the right (sin(30), log2(4), etc.)
This capability can be used with the following functions: , , ,
(), (), (), 5(), 2(), ,
, (), @(Abs).
Overwrite Input Mode (Linear Display only)
You can select either insert or overwrite as the input mode, but only while
Linear Display is selected. In the overwrite mode, text you input replaces the
text at the current cursor location. You can toggle between the insert and
overwrite modes by performing the operations: &(INS). The cursor
appears as “I” in the insert mode and as “ ” in the overwrite mode.
Note: Natural Display always uses the insert mode, so changing display
format from Linear Display to Natural Display will automatically switch to
the insert mode.
Correcting and Clearing an Expression
To delete a single character or function: Move the cursor so it is directly to
the right of the character or function you want to delete, and then press &.
In the overwrite mode, move the cursor so it is directly under the character
or function you want to delete, and then press &.
To insert a character or function into a calculation: Use Band Cto
move the cursor to the location where you want to insert the character or
function and then input it. Be sure always to use the insert mode if Linear
Display is selected.
To clear all of the calculation you are inputting: Press .
Toggling Calculation Results
While Natural Display is selected, each press of 5will toggle the currently
displayed calculation result between its fraction form and decimal form, its
form and decimal form, or its Pform and decimal form.


