Introduction
This manual provides detailed instructions for the proper use and maintenance of your Casio FX-991ES Plus-2 Scientific Calculator. This calculator features a natural display (Natural V.P.A.M.) that presents mathematical expressions and results in a textbook-like format, enhancing comprehension and ease of use. Please read this manual thoroughly to ensure optimal performance and longevity of your device.
Setup and Initial Operations
Powering On and Off
To turn on the calculator, press the ON button. To turn off the calculator, press SHIFT followed by AC (OFF). The calculator also features an auto power-off function that activates after approximately 10 minutes of inactivity to conserve battery life.
Battery Information
The Casio FX-991ES Plus-2 is powered by 1 Lithium Ion battery (included). It also features solar power, which extends battery life under sufficient lighting conditions. Ensure the calculator is exposed to light for optimal solar charging.
Image: Front view of the Casio FX-991ES Plus-2 Scientific Calculator with its sliding protective cover. The display shows "CASIO fx-991ES PLUS 2nd edition NATURAL V.P.A.M." and the key layout is visible.
Initial Settings (MODE/SETUP)
Upon first use or after a battery change, it is recommended to configure the calculator's settings. Press MODE/SETUP to access various modes and settings. Use the arrow keys to navigate and press the corresponding number to select an option. Common settings include:
- Comp (1): For general arithmetic calculations.
- Stat (2): For statistical calculations.
- Table (3): For generating number tables from functions.
- Display Format: Adjust decimal places, scientific notation, etc.
- Angle Unit: Select Degrees, Radians, or Gradians.
Operating Instructions
Basic Arithmetic Calculations
Enter numbers and operators in sequence. Press = to display the result. For example, to calculate 2 + 3, press 2 + 3 =.
Using Natural Display (V.P.A.M.)
The Natural Display feature allows input and display of fractions, roots, and other expressions as they appear in textbooks. For example, to input a fraction like 1/2, press the fraction key (a b/c or similar, usually above the DEL key) and enter the numerator and denominator. To switch between fractional and decimal results, press S↔D.
Scientific Functions
Access scientific functions (e.g., sin, cos, tan, log, ln, powers, roots) by pressing the corresponding key. For inverse functions or secondary functions printed above the keys, press SHIFT first, then the desired function key.
- Trigonometric Functions: sin, cos, tan. Ensure the correct angle unit (Deg, Rad, Gra) is selected in SETUP.
- Logarithmic Functions: log (base 10), ln (natural logarithm).
- Powers and Roots: Use x² for squares, SHIFT x² for square roots, x³ for cubes, SHIFT x³ for cube roots, and x□ for custom powers.
Memory Functions
The calculator includes independent memory (M) and several variable memories (A, B, C, D, E, F, X, Y). To store a value, enter the value, press STO (SHIFT RCL), then the desired memory key (e.g., A). To recall a value, press RCL, then the memory key.
Maintenance
Cleaning
Wipe the calculator with a soft, dry cloth. Do not use harsh chemicals, abrasive cleaners, or excessive moisture, as these can damage the display or casing.
Storage
When not in use, store the calculator in its protective case in a cool, dry place away from direct sunlight and extreme temperatures. Avoid placing heavy objects on top of the calculator.
Image: Rear view of the Casio FX-991ES Plus-2 Scientific Calculator, showing its plain black casing and four rubber feet for stability.
Battery Replacement
If the display becomes dim or operations become unreliable, the battery may need replacement. Refer to the back of the calculator for battery type (1 Lithium Ion battery). To replace, carefully open the battery compartment on the back, remove the old battery, and insert a new one with the correct polarity. Dispose of old batteries according to local regulations.
Image: Close-up of the back of the Casio FX-991ES Plus-2 Scientific Calculator, displaying regulatory markings, battery information (DC 1.5V, LR44 x1), and manufacturer details.
Troubleshooting
- Calculator does not turn on:
- Ensure the ON button is pressed firmly.
- Check battery charge. Replace if necessary.
- Ensure sufficient light for solar panel operation.
- Display is dim or difficult to read:
- Adjust display contrast: Press SHIFT then MODE/SETUP, then navigate to Contrast.
- Check battery charge.
- Incorrect calculation results:
- Verify the correct mode (e.g., COMP, STAT) is selected.
- Check angle unit setting (Deg, Rad, Gra).
- Clear all memory and settings: Press SHIFT 9 (CLR), then select 3 (All), then = (Yes).
- Calculator freezes or behaves erratically:
- Perform a reset by pressing the RESET button on the back (if available, usually a small hole requiring a thin object). If no reset button, remove and reinsert the battery.
Specifications
| Feature | Detail |
|---|---|
| Model Number | FX-991ESPLUS-2SETD |
| Brand | Casio |
| Calculator Type | Engineering/Scientific |
| Power Source | Battery Powered (1 Lithium Ion battery included), Solar Power |
| Screen Size | 2 Centimeters (Visible screen diagonal: 1" / 2 cm) |
| Color | Black |
| Product Dimensions | 19.69 x 19.69 x 11.02 inches |
| Item Weight | 4.2 ounces |
| First Available | April 30, 2020 |
Image: The Casio FX-991ES Plus-2 Scientific Calculator shown next to a hand for scale, with dimensions indicating a length of 6.6 inches (16 cm).
Warranty and Support
For warranty information and customer support, please refer to the official Casio website or the documentation included with your purchase. Casio provides support for its products to ensure customer satisfaction.
You can visit the official Casio support page for calculators at www.casio.com/us/support/calculators/ for FAQs, downloads, and service information.
