• Answer memory contents are not change if an error occurs
during the current calculation.
•Answer memory contents are mainiained even if you press
the [AC]key, change the calculation mode, or turn off the
calculator.
Example: 258
456 = 714
987714 = 273
[2] [5] [8] [] [4] [5] [6] [=]
[9] [8] [7] [
] [Ans] [=]
• If you need to recall Answer Memory contents after pressing
[AC], press [Ans] [=] key.
Independent Memory
Addition and subtraction (to and from sum) results can be
stored directly in memory.Results can also be totalized in
memory, making it easy to calculate sums.
• You can insert the “M” variable into a calculation, which tells
the calculator to use the current independent memory
contents at that location. The following is the key operation
for inserting the “M” variable.
[ALPHA] [M+] (i.e. the character “M”)
•The “M” indicator appears in the upper left of the display
when there is any value other
zero stored in independent
memory.
•Independent memory contents are maintained even if you
press the [AC] key, change the calculation mode, or turn off
the calculator.
To clear the independent memory contents, press
[0] [SHIFT] [RCL] [M+]
This clears independent memory and causes the “M” indicator
to disappear from the display.
Example: 38
9 = 47 [3] [8] [] [9] [M+]
) 458 = 37 [4] [5] [] [8] [M+]
) 273 = 81 [2] [7] [] [3] [SHIFT] [M+]
) 964 = 24 [9] [6] [] [4] [M+]
(Total) 27 [RCL] [M+] (i.e. “M”)
Variable memories
Six variables named A, B, C, D, X, and Y can be used for storage
of individual values at the same time, and can be recalled
when desired.
• You can assign a specific value or when formulas are input,
the result of the formula’s calculation to a variable.
•To check the contents of a variable, press [RCL] then the
corresponding key for the variable.
Example: to recall the contents of variable A, press
press [RCL] [(–)]
• Variables can be used inside of an expression.
Example: to multiply the contents of variable A by the
contents of variable B
[ALPHA] [(–)] (i.e. “A”) [
] [ALPHA] [º ' "] (i.e. “B”)
•Variable contents are protected even when the power is
turned OFF.
Example:Input 123 into memory “A”
Input the result of 123
456 into memory “B”
Input the results of A
B into memory “C”
[1] [2] [3] [SHIFT] [RCL] [(–)]
[1] [2] [3] [] [4] [5] [6]
[SHIFT] [RCL] [º ' "]
[ALPHA] [(–)] [
]
[ALPHA] [º ' "] [=]
To clear the contents of a specific variable, press:
[0] [SHIFT] [RCL] and then press the key for the name of the
variable whose contents you want to clear e.g. press [(–)] for
the variable “A”.
The contents of all memories can be cleared at the same time
by pressing
[SHIFT] [9] [2]
then press [=] to confirm the operation or press
[AC] to cancel this operation.
“CALC” function
•The CALC function lets you input a calculation expression
that contains variables, and then assign values to the
variables and perform the calculation.
• You can use the CALC in the COMP Mode ([MODE] [1]) and in
the CMPLX Mode ([MODE] [2]).
The following types of expression can be used with CALC.
• Expressions that contain variables
Example: 2X + 3Y, 5B + 3i, 2AX + 3BY +C
• Multi-statements
Example: X + Y : X (X + Y)
• Expressions with a single variable on the left
Example: {variable} = {expression}
The expression on the right of the equal sign (input using
[ALPHA] [CALC] [=]) can contain variables.
Example: Y = 2X, A = X
2
+ X + 3
To start a CALC operation after inputting an expression, press
the [CALC] key.
LINE
[5] [
] [ALPHA] [(–)] (A)
[CALC]
Prompts for input
of a value for A.
Current value of A
[7] [=]
[CALC] (or [=])
[9] [=]
• To exit CALC, press [AC].
• If the expression you are using contains more than one
variable, an input prompt appears for each one.
“Solve” functions
The solve feature lets you solve an expression using variable
values you want without the need to transform or simplify the
expression. For example, in the expression "B=AX–5", you can
define A, B to findX, or define A, X to find B, or define B, X to find
A.
Newton's method is used for solving functions, in which, error
can occur. Certain expressions or initial values may result in
error without convergence of results.
Example: Y=AX
2
6X9
[AC] [ALPHA] [Y] [ALPHA] [=]
[ALPHA] [A] [ALPHA] [X] [X
2
]
[] [6] [ALPHA] [X] [] [9]
[SHIFT] [CALC] (SOLVE)
Prompts for input
of a value for Y.
Current value of Y
[0] [=]
[2] [=]
[=]
Solution Screen
• The “L–R=” (left side – right side form result) shows the result
when the obtained solution is assigned to the solution
variable. The closer this value is to zero, the higher is the
precision of the obtained solution.
• If you want to restart the function solving for the same
formula, you can press [=] once more to recycle the solving
procedure. You will be asked again to input the value for all
the variables.If you want to exit from solving function, press
[AC].
Function Calculations
The functions available to you depends on the calculation
mode you are in. The
explanations in this section are mainly
about the functions that are available in all calculation modes.
All of the examples in this section show operation in the COMP
Mode ( [MODE] [1] ).
Trigonometric functions and inverse trigonometric
functions
•The angle unit required by trigonometric and inverse
trigonometric functions is one specified as the calculator’s
default angle unit. Before performing a calculation, be sure
to specify the default angle unit you want to use.
Hyperbolic and Inverse Hyperbolic Functions
Pressing the [hyp] key displays
a menu of functions.
Press the number key that
corresponds to the function
you want to input.
2
3
2
3
2
3
2
3
1
3
4 +2
7
Math
4
3||
Math
4
3
+1||
Math
2+3||
√
---
Math
√
---
2+3+4||
Math
2
5
98
25
2
5
{
1 +
}
x2
Math
To selectthis mode
COMP
CMPLX
STAT
BASE-N
EQN
MATRIXTABLEVECTORFor this type of operationGeneral calculationsComplex number calculationsStatistical and regressioncalculationsBase-n calculations (binary,octal, decimal, hexadecimal)Equation solutionMatrix calculationsGeneration of a number tablebased on an expressionVector calculationsPress
Function Key Operation StepsImproper Fraction 9Mixed Fraction 13log(a, b) (logarithm) 6
10
x
(Power of 10) 4
e
x
(Power of e) 4Square Root 4Cube Root 9Square, Cube 4
5 lacorpiceR
Power 4Power Root 9
8 largetnI
6 evitavireD
∑ Calclation 8Absolute Value 4Parentheses 1[ ][SHIFT] [ ] ( )[log ][SHIFT] [log] (10 )[SHIFT] [In] (e )
[
√
---
]
[SHIFT] [
√
---
] (
3
√
---
)
[x
2
] , [SHIFT] [x
2
] (x
3
)
[x
–1
]
[x
]
[SHIFT] [x
] (
√
---
)
[∫][SHIFT] [∫ ] ( )[SHIFT] [log ] (
∑
)
[SHIFT] [hyp] (Abs)[ ( ] or [ ) ]
d
dx
1 :ab/c2 : d/c
3 : CMPLX4 : STAT
5 : Disp6 :CONT
3 2 13 3 15 2 90 78 1170
√
---
+
√
---
3+ 6
Math
√
---
69
Angle Unit
Selection
Input of
Angle Value
Input Value Range
for √
--
Form
Display
Deg Units of 15
º
|x| < 9
10
9
Rad
Multiples of
1
π radians
|x| < 20π
Gra Multiples of
50
grads |x| < 10000
__
12
__
3
a b
c
± --------- ± ---------
√
--
d e
f
√
--
√
---
+
√
---
5 449489743
Math
69cos (30
Math
3
2
√
---
/
√
--
√
--
√
--
------------ = 9.899494937cos
-1
(05
Math
π
1
3
/
± a* b ± d* e
c*
√
--
√
--
--------------------------
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
√
--
d
c
b
c
√
---
x
√
---
5 477225575
Math
56
√
---
x
√
---
30
Math
√
------
56
/
√
---
x
√
---
30
Math
√
------
56
/
(Linear format) CalculationExample Operation Result
Percentage
26% of $15.00
Premium
15% increase from
$36.20
Discount
4% discount from
$47.50
Ratio
75 is what % of 250?
Rate of change
141 is an increase of
what % from 120?
Rate of change
240 is a decrease of
what % from 300?
[1][5][
][2][6][SHIFT][ ( ]
[=]
[3][6][
•
][2][][3][6][
.
][2]
[][1][5][SHIFT][ ( ][=]
[4][7][
•
][5][][4][7][
.
][5]
[][4][SHIFT][ ( ][=]
[7][5][
][2][5][0]
[SHIFT][ ( ][=]
[ ( ][1][4][1][][1][2][0][ ) ]
[][1][2][0][SHIFT] [ ( ][=]
[ ( ][2][4][0][][3][0][0][ ) ]
[][3][0][0][SHIFT] [ ( ][=]
3.9
41.63
45.6
30
17.5
–20
(Linear format) CalculationExample Operation Result
To express 2.258 degrees
in deg/min/sec.
To perform the calculation:
12
º
34'56"3.45
[2][
•
][2][5][8][=]
[º' "]
[º' "]
[1][2][º' "][3][4][º' "][5][6]
[º' "][
][3][
•
][4][5][=]
[º' "]
[º' "]
2.258
2
º
15’28.8”
2.258
43
º
24’31.2”
43.40866667
43
º
24’31.2”
Disp
5
x
6
30
/
5
x
67x8
0
/
7x8
56
2
3
1
2
7
6
1
4
2
3
11
12
2 3+1 2
7 6
314 + 1 2 3
41112
2
3
1
2
7
6
+
Math
9x3
27
4x6
24
2+3
5
||
0
/
412x3 58-71
7 6496
41 2x3 58+6 4
21 1496
41 2x3 58+6 4||
0
/
41 2x3 58||
0
/
123 A
123
AxB
6898824
123x456 B
56088
/
5xA||
A?
0
/
5xA
35
A?
7
5xA
45
Y=AX
2
+6X-9
0
/
Y?
0
/
A?
0
/
Solve for X
0
/
Y=AX
2
+6X-9
X= 1.098076211
L-R=0
/
//
(Linear format) CalculationExample Operation Result
23 + 4.5 –53 =–25.5
56
(–12)(–2.5)
=268.8
(4.5
10
75
)(–2.3
10
–79
) = –1.03510
–3
(110
5
)7=
14285.71429
2
3 ( 4 5 ) = 29
( 7
2 ) ( 8 5 )
= 65
[2][3][
][4][
.
][5]
[][5][3][=]
[5][6][
][(–)][1][2]
[][(–)][2][
.
][5][=]
[4][
.
][5][x10
x
][7][5] []
[(–)][2][
.
][3][x10
x
]
[(–)][7][9][=]
[1][x10
x
][5][][7][=]
[2][
][3][][(][4][][5][=]
Closed parentheses
occurring immediately
before operation of the
[=] key may be omitted.
[( ][7][][2][ )][( ][8][][5][=]
A multiplication sign [
]
occurring immediately
before an open parantheses
can be omitted.
–25.5
268.8
–1.035x
10
–3
14285.71429
29
65
258+456
714
987-Ans
273
(Linear format) CalculationExample Operation Result
sin 63
º
52'41"
= 0.897859012
cos (π/3 rad) = 0.5
tan (–35 grad)
= –0.6128007881
2sin45
º
cos65
º
= 0.5976724775
sin
–1
0.5 = 30
cos
–1
(√2/2)
= 0.7853981634 rad
tan
–1
0.741
= 36.53844577
º
= 36
º
32' 18.4"
2.5
(
sin
–1
0.8cos
–1
0.9)
= 68
º
13'13.53"
Angle unit: Deg
[sin] [6] [3] [
º
' "] [5] [2]
[
º
' "] [4] [1] [
º
' "][ ) ] [=]
Angle unit: Rad
[cos] [
SHIFT
] [x10
x
] [] [3]
[ ) ] [=]
Angle unit: Gra
[tan] [(–)] 35 [=]
Angle unit: Deg
[2] [sin] [4] [5] [ ) ]
[cos] [6] [5] [ ) ] [=]
Angle unit: Deg
[
SHIFT
][sin] [.] [5] [ ) ] [=]
Angle unit: Rad
[
SHIFT
] [cos][ [√
---
] [2] [ ) ]
[] [2] [ ) ] [=]
Angle unit: Deg
[
SHIFT
] [tan] [.] [7] [4] [1]
[ ) ] [=]
[º ' "]
Angle unit: Deg
[2] [.] [5] [
] [(] [
SHIFT
]
[sin] [.] [8] [ ) ] [] [
SHIFT
]
[cos] [.] [9] [)] [ ) ] [=]
[º ' "]
0.897859012
0.5
–0.6128007881
0.5976724775
30
0.7853981634
36.53844577
36
º
32’18.4”
68.22042398
68
º
13’13.53”
1 :sinh2 : cosh
3 : tanh4 : sinh
-1
5 : cosh
-1
6 : tanh
-1
2-lines display
Dual Power Scientific Calculator with
Natural Textbook Display
Please read before using.
DS-991ES
Manual
View the manual for the Datexx DS-991ES here, for free. This manual comes under the category Calculators and has been rated by 1 people with an average of a 7.5. This manual is available in the following languages: English. Do you have a question about the Datexx DS-991ES or do you need help? Ask your question here
Do you have a question about the Datexx DS-991ES and the answer is not in the manual? Ask your question here. Provide a clear and comprehensive description of the problem and your question. The better your problem and question is described, the easier it is for other Datexx DS-991ES owners to provide you with a good answer.
Number of questions: 0
Datexx DS-991ES specifications
Below you will find the product specifications and the manual specifications of the Datexx DS-991ES.
Can't find the answer to your question in the manual? You may find the answer to your question in the FAQs about the Datexx DS-991ES below.
What is an Overflow error?
An Overflow error usually occurs when the sum result is longer than the calculator can show.
A battery in my Calculator has started to corrode. Is the device still safe to use?
The product can still be used safely after proper cleaning. Remove the battery with gloves and clean the battery compartment with a toothbrush and vinegar. After drying, new batteries can be inserted into the device.
What does AC stand for on my calculator?
AC stands for 'all clear'. You clear the entire memory of the calculator with this button.
Is the manual of the Datexx DS-991ES available in English?
Yes, the manual of the Datexx DS-991ES is available in English .
Need help?
Do you have a question about the Datexx DS-991ES and the answer is not in the manual? Ask your question here. Provide a clear and comprehensive description of the problem and your question. The better your problem and question is described, the easier it is for other Datexx DS-991ES owners to provide you with a good answer.
Number of questions: 0