CASIO FX-991MS (03) PDF MANUAL

Before starting a calculation, you must first enter the correct mode. The following table shows the modes and required key operations for the fx-570MS and fx-991MS.

Pressing the MODE key more than three times displays additional setup screens. These screens are used to change the calculator setup.

Note: To return the calculation mode and setup to the initial defaults, press SHIFT CLR 2 (Mode) =. The initial defaults are:

Calculation Mode: COMP

Angle Unit: Deg

Exponential Display Format: Norm 1, Eng OFF

Complex Number Display Format: a+bi

Fraction Display Format: ab/c

Decimal Point Character: Dot

Mode indicators appear in the upper part of the display, except for the BASE indicators, which appear in the exponent part of the display.

Engineering symbols are automatically turned off while the calculator is in the BASE Mode.

You cannot make changes to the angle unit or other display format (Disp) settings while the calculator is in the BASE Mode.

The COMP, CMPLX, SD, and REG modes can be used in combination with the angle unit settings.

Be sure to check the current calculation mode (SD, REG, COMP, CMPLX) and angle unit setting (Deg, Rad, Gra) before beginning a calculation.

Replay copy lets you recall multiple expressions from replay memory so they are connected as a multi-statement on the screen.

Example:

If replay memory contains: 1+1, 2+2, 3+3, 4+4, 5+5, 6+6

To create the multi-statement: 4 + 4:5 + 5:6 + 6

1. Use the up and down arrow keys to display the expression 4 + 4.

2. Press SHIFT ▲(COPY).

The screen will now show “4+4:5+5:6+6”. You can also edit expressions on the display and perform other multi-statement operations. Only the expressions in replay memory starting from the currently displayed expression and continuing to the last expression are copied.

CALC memory lets you temporarily store a mathematical expression (up to 79 steps) that you need to perform a number of times using different values. This function can be used in the COMP and CMPLX Modes only.

Example: Calculate the result for Y = X² + 3X – 12 when X = 7 (Result: 58), and when X = 8 (Result: 76).

1. Input the function: ALPHA Y ALPHA = ALPHA X x² + 3 ALPHA X – 12

2. Store the expression: Press CALC.

3. The calculator will prompt “X?”. Input 7 and press =. The result 58 is displayed.

4. To calculate for X=8, press CALC again. At the “X?” prompt, input 8 and press =. The result 76 is displayed.

Note that the expression you store is cleared whenever you start another operation, change to another mode, or turn off the calculator.

The SOLVE function lets you solve an expression using variable values you want, without the need to transform or simplify the expression.

Example: Using the formula B = AC – (1/2)DC², calculate the initial velocity A for a height of B = 14 meters, time C = 2 seconds, and gravitational acceleration D = 9.8 m/s². (Result: A = 16.8)

1. Input the expression: ALPHA B ALPHA = ALPHA A x ALPHA C – ( 1 ab/c 2 ) x ALPHA D x ALPHA C x²

2. Press SHIFT SOLVE.

3. The calculator will prompt for the value of B. Enter 14 =.

4. The calculator will then prompt for A. Press the down arrow to skip to the next variable.

5. The calculator will prompt for C. Enter 2 =.

6. The calculator will prompt for D. Enter 9.8 =.

7. Move the cursor back up to the “A=…” line and press SHIFT SOLVE to solve for A.

Limitations:

Since the SOLVE function uses Newton’s Method, certain initial values (assumed values) can make it impossible to obtain solutions. If this happens, try inputting another value that you assume to be near the solution and perform the calculation again.

The SOLVE function may be unable to obtain a solution, even though a solution exists.

Solutions for the following types of functions tend to be difficult to calculate: Periodic functions (i.e. y = sin x), functions whose graph produce sharp slopes (i.e. y = e^x, y = 1/x), and discontinuous functions (i.e. y = √x).

If an expression does not include an equals sign (=), the SOLVE function produces a solution for expression = 0.

Turning on engineering symbols allows you to use them inside your calculations in COMP, EQN, and CMPLX modes.

1. To turn engineering symbols on and off, press the MODE key a number of times until you reach the setup screen showing “Disp”.

2. Press 1. On the engineering symbol setting screen that appears, press 1 (Eng ON) or 2 (Eng OFF).

When Eng ON is selected, “Eng” is indicated on the display.

Example: 9 ÷ 10 = 0.9 m (milli)

1. Turn Eng ON.

2. Input 9 ÷ 10 =.

3. The display will show “900. m”. The “m” represents milli (10⁻³).

When engineering symbols are turned on, even standard (non-engineering) calculation results are displayed using engineering symbols. For displayed values, the calculator selects the engineering symbol that makes the numeric part of the value fall within the range of 1 to 1000. Engineering symbols cannot be used when inputting fractions.

The following are the nine symbols that can be used when engineering symbols are turned on.

Use the MODE key to enter the CMPLX Mode (MODE 2) when you want to perform calculations that include complex numbers.

The current angle unit setting (Deg, Rad, Gra) affects CMPLX Mode calculations.

You can use variables A, B, C, and M only in the CMPLX Mode. Variables D, E, F, X, and Y are used by the calculator, which frequently changes their values. You should not use these variables in your expressions.

The indicator “R↔I” in the upper right corner of a calculation result display indicates a complex number result. Press SHIFT Re-Im to toggle the display between the real part and imaginary part of the result.

Example: (2+3i) + (4+5i) = 6+8i

1. Enter CMPLX mode.

2. Input: 2 + 3 i + 4 + 5 i =

3. The real part (6) is displayed. Press SHIFT Re-Im to view the imaginary part (8i).

You can determine the absolute value (r) and argument (θ) of a complex number z = a + bi.

Example: To determine the absolute value (r) and argument (θ) of 3+4i (Angle unit: Deg).

To find the absolute value (r=5): Press SHIFT Abs ( 3 + 4 i ) =

To find the argument (θ=53.13010235°): Press SHIFT arg ( 3 + 4 i ) =

To find the conjugate: For any complex number z where z = a+bi, its conjugate is z = a-bi.

Example: To determine the conjugate of the complex number 1.23 + 2.34i (Result: 1.23 – 2.34i).

Press SHIFT Conjg ( 1 . 23 + 2 . 34 i ) =

You can convert a rectangular form complex number to its polar form, and a polar form complex number to its rectangular form. Press SHIFT Re-Im to toggle the display between the absolute value (r) and argument (θ).

Example: 1 + i ↔ 1.414213562 ∠ 45 (Angle unit: Deg)

1. Input 1 + i.

2. To display in polar form, press SHIFT r∠θ =. The display shows the value of r. Press SHIFT Re-Im to see the value of θ.

3. To convert back to rectangular form, with the polar form displayed, press SHIFT a+bi =. The display shows the real part. Press SHIFT Re-Im to see the imaginary part.

You can also select the default display format for complex number calculation results:

1. Press MODE repeatedly until the “Disp” screen appears.

2. Press 1, then use the right arrow key.

3. Press 1 for rectangular form (a+bi) or 2 for polar form (r∠θ).

Enter the BASE Mode (MODE MODE 3) to perform calculations using Base-n values. In addition to decimal values, calculations can be performed using binary, octal, and hexadecimal values. You can specify the default number system for all input and displayed values.

Key points:

You cannot use scientific functions in binary, octal, decimal, and hexadecimal calculations. You cannot input values that include a decimal part and an exponent.

If you input a value that includes a decimal part, the unit automatically cuts off the decimal part.

Negative binary, octal, and hexadecimal values are produced by taking the two’s complement.

You can use the logical operators: and, or, xor, xnor, Not, and Neg.

Allowable ranges:

Example 1 (Binary): 10111₂ + 11010₂ = 110001₂

In Binary mode: 10111 + 11010 =

Example 2 (Convert): To convert the value 22₁₀ to its binary, octal, and hexadecimal equivalents.

In Decimal mode: Enter 22 =. Then press the BIN key (shows 10110), OCT key (shows 26), and HEX key (shows 16).

If a conversion results in a value outside the allowable range of the target number system, a “Math ERROR” will occur.

Enter the SD Mode (MODE MODE 1) to perform a calculation involving normal distribution. In the SD and REG Modes, the M+ key operates as the DT key.

1. Press SHIFT DISTR to produce the screen with the following options:

1: P( 2: Q( 3: R( 4: →t

2. Input a value from 1 to 4 to select the probability distribution calculation you want to perform.

Example: To determine the normalized variate (→t) for x = 53 and normal probability distribution P(t) for the following data: 55, 54, 51, 55, 53, 53, 54, 52.

1. Enter SD Mode and clear statistical memory (SHIFT CLR 1 =).

2. Input the data: 55 DT 54 DT 51 DT 55 DT 53 DT 53 DT 54 DT 52 DT.

3. To find →t: 53 SHIFT DISTR 4 (→t) =. Result: -0.284747398.

4. To find P(t): With the previous result displayed, SHIFT DISTR 1 (P() ANS ) =. Or press SHIFT DISTR 1 (P() (-) 0.28 ) =. Result: 0.38974.

Enter the COMP Mode (MODE 1) for these calculations.

Differential Calculations

This procedure obtains the derivative of a function. Three inputs are required: the function of variable x, the point (a) at which the differential coefficient is calculated, and the change in x (Δx).

Syntax: SHIFT d/dx [expression] , [a] , [Δx] )

Example: To determine the derivative at point x = 2 for the function y = 3x² – 5x + 2, when Δx = 2 × 10⁻⁴ (Result: 7).

Input: SHIFT d/dx 3 ALPHA X x² – 5 ALPHA X + 2 , 2 , 2 EXP (-) 4 ) =

Notes: You can omit input of Δx. Select Rad (Radian) for the angle unit setting when performing trigonometric function differential calculations.

Integration Calculations

This procedure obtains the definite integral of a function using Simpson’s rule. Four inputs are required: a function with the variable x; a and b, which define the integration range; and n, the number of partitions (an integer from 1 to 9, equivalent to N=2ⁿ).

Syntax: ∫dx [expression] , [a] , [b] , [n] )

Example: ∫(from 1 to 5) (2x² + 3x + 8) dx, with n=6 (Result: 150.6666667).

Input: ∫dx 2 ALPHA X x² + 3 ALPHA X + 8 , 1 , 5 , 6 ) =

Notes: You can skip input of n. Internal integration calculations may take time to complete. Select Rad (Radian) for the angle unit setting when performing trigonometric function integration calculations.

Enter the MAT Mode (MODE MODE MODE 2) to perform matrix calculations. You can have up to three matrices (A, B, C) in memory. Results are stored in MatAns memory.

Creating a Matrix

1. Press SHIFT MAT 1 (Dim).

2. Select a matrix name to assign: 1 (A), 2 (B), or 3 (C).

3. Specify the dimensions. Input the number of rows (m) and press =. Input the number of columns (n) and press =.

4. Input the value for each element, pressing = after each one. You can use the cursor keys to move between elements.

5. After inputting all elements, press AC to exit the matrix screen.

Editing the Elements of a Matrix

1. Press SHIFT MAT 2 (Edit).

2. Select the name of the matrix you want to edit: 1 (A), 2 (B), or 3 (C).

3. Use the cursor keys to move to the element you want to change, input the new value, and press =.

4. Press AC to exit.

First, ensure the required matrices have been created in MAT mode.

Matrix Addition, Subtraction, and Multiplication

To perform an operation, recall the matrix names from memory.

Example (Multiplication): MatA × MatB

Input: SHIFT MAT 3 (Mat) 1 (A) × SHIFT MAT 3 (Mat) 2 (B) =

Note: An error occurs if dimensions are not compatible for the operation.

Calculating the Scalar Product

Example: 3 × MatC

Input: 3 × SHIFT MAT 3 (Mat) 3 (C) =

Obtaining the Determinant

This applies to square matrices only.

Example: Det(MatA)

Input: SHIFT MAT > 1 (Det) SHIFT MAT 3 (Mat) 1 (A) =

Transposing a Matrix

Example: Trn(MatB)

Input: SHIFT MAT > 2 (Trn) SHIFT MAT 3 (Mat) 2 (B) =

Inverting a Matrix

This applies to square matrices only.

Example: MatC⁻¹

Input: SHIFT MAT 3 (Mat) 3 (C) x⁻¹ =

Determining the Absolute Value of a Matrix

Example: Abs(MatAns)

Input: SHIFT Abs SHIFT MAT 3 (Mat) 4 (Ans) =

Enter the VCT Mode (MODE MODE MODE 3) to perform vector calculations. You can have up to three vectors (A, B, C) in memory. Results are stored in VctAns memory.

Creating a Vector

1. Press SHIFT VCT 1 (Dim).

2. Select a vector name to assign: 1 (A), 2 (B), or 3 (C).

3. Specify the dimension (2 or 3) and press =.

4. Input the value for each element, pressing = after each one. You can use the cursor keys to move between elements.

5. After inputting all elements, press AC to exit the vector screen.

Editing Vector Elements

1. Press SHIFT VCT 2 (Edit).

2. Select the name of the vector you want to edit: 1 (A), 2 (B), or 3 (C).

3. Use the cursor keys to move to the element you want to change, input the new value, and press =.

4. Press AC to exit.

First, ensure the required vectors have been created in VCT mode.

Adding and Subtracting Vectors

Example: VctA + VctB

Input: SHIFT VCT 3 (Vct) 1 (A) + SHIFT VCT 3 (Vct) 2 (B) =

Note: An error occurs if vectors have different dimensions.

Calculating the Scalar Product of a Vector

Example: 5 × VctC

Input: 5 × SHIFT VCT 3 (Vct) 3 (C) =

Calculating the Inner Product of Two Vectors

Example: VctA • VctB

Input: SHIFT VCT 3 (Vct) 1 (A) SHIFT VCT > 1 (Dot) SHIFT VCT 3 (Vct) 2 (B) =

Calculating the Outer Product of Two Vectors

Example: VctA × VctB

Input: SHIFT VCT 3 (Vct) 1 (A) × SHIFT VCT 3 (Vct) 2 (B) =

Determining the Absolute Value of a Vector

Example: Abs(VctC)

Input: SHIFT Abs SHIFT VCT 3 (Vct) 3 (C) =

Enter the COMP Mode (MODE 1) to perform metric conversions. A total of 20 different conversion pairs are built-in.

When inputting a negative value, enclose it within parentheses.

Example: To convert -31 degrees Celsius to Fahrenheit.

The Celsius-to-Fahrenheit conversion pair number is 38.

Input: ( (-) 31 ) SHIFT CONV 38 =

The result displayed is -23.8.

Based on NIST Special Publication 811 (1995).

A total of 40 commonly-used scientific constants are built-in for quick lookup. Use the COMP mode (MODE 1).

Simply input the number that corresponds to the scientific constant you want to look up and it appears instantly on the display. Use the SHIFT CONST key combination followed by the constant number.

Example: To determine how much total energy a person weighing 65kg has (E = mc², where c is the speed of light in a vacuum, constant number 28).

Input: 65 × ( SHIFT CONST 28 ) x² =

Result: 5.841908662 × 10¹⁸

Based on ISO Standard (1992) data and CODATA recommended values (1998).

Either of the following symptoms indicates battery power is low and that the battery should be replaced:

Display figures are dim and difficult to read in areas where there is little light available.

Nothing appears on the display when you press the ON key.

Continued use of the calculator when the battery is low can result in improper operation. Replace the battery as soon as possible when display figures become dim.

The fx-991MS uses a TWO WAY POWER system with a solar cell and a G13 Type (LR44) button battery.

1. Remove the five screws that hold the back cover in place and then remove the back cover.

2. Remove the old battery.

3. Wipe off the sides of a new battery with a dry, soft cloth. Load it into the unit with the positive (+) side facing up (so you can see it).

4. Replace the back cover and secure it in place with the five screws.

5. Press ON to turn power on. Be sure not to skip this step.

This calculator is powered by a single G13 Type (LR44) button battery.

1. Press SHIFT OFF to turn off power.

2. Remove the screw that holds the battery cover in place and then remove the battery cover.

3. Remove the old battery.

4. Wipe off the sides of a new battery with a dry, soft cloth. Load it into the unit with the positive (+) side facing up (so you can see it).

5. Replace the battery cover and secure it in place with the screw.

6. Press ON to turn power on.

Yes, the calculator power automatically turns off if you do not perform any operation for about six minutes. When this happens, press the ON key to turn power back on.

Power Supply:

fx-570MS: Single G13 Type button battery (LR44)

fx-991MS: Solar cell and a single G13 Type button battery (LR44)

Battery Life:

fx-570MS: Approximately 9,000 hours continuous display of flashing cursor. Approximately 3 years when left with power turned off.

fx-991MS: Approximately 3 years (1 hour use per day).

Dimensions: 12.7 (H) × 78 (W) × 154.5 (D) mm (1/2″ (H) × 3 1/16″ (W) × 6 1/16″ (D))

Weight: 105 g (3.7 oz) including battery

Power Consumption: 0.0002 W

Operating Temperature: 0°C to 40°C (32°F to 104°F)