1. Introduction
This manual provides essential instructions for the proper use and maintenance of your Casio DS-1JT heavy-duty desktop calculator. Designed for durability and efficiency, this calculator features a 300-step check function, tax calculation capabilities, and a robust design suitable for demanding environments. Please read this manual thoroughly before using the calculator to ensure optimal performance and longevity.
2. Product Overview
The Casio DS-1JT is a heavy-duty desktop calculator featuring a classic design and a dark gray plastic case that enhances its durability. It is equipped with a large LCD display and fade-resistant keys for reliable long-term use.

Front view of the Casio DS-1JT heavy-duty desktop calculator, showing its large LCD display and key layout.
A 360-degree rotating view of the Casio DS-1JT desktop calculator, showcasing its design from all angles.
3. Setup
3.1 Power Source
The Casio DS-1JT calculator operates on dual power: solar and battery. It comes with one battery pre-installed. The solar panel provides power in well-lit environments, while the battery ensures continuous operation in low-light conditions.
3.2 Initial Use
Upon first use, ensure the calculator is exposed to sufficient light for the solar panel to activate, or press the AC/ON button to power it on. No additional setup is typically required for basic operation.
4. Operating Instructions
4.1 Basic Calculations
- Addition (+): Enter the first number, press '+', enter the second number, press '='.
- Subtraction (-): Enter the first number, press '-', enter the second number, press '='.
- Multiplication (×): Enter the first number, press '×', enter the second number, press '='.
- Division (÷): Enter the first number, press '÷', enter the second number, press '='.
4.2 Check and Correct Function (300 Steps)
This function allows you to review and correct up to 300 calculation steps. This is particularly useful for preventing errors in long calculations.
- RECHECK: Press this button to review previous calculation steps.
- BACK/FORWARD: Use these buttons to navigate through the recorded steps.
- CORRECT: If an error is found, navigate to the incorrect step and enter the correct value. The calculator will automatically adjust subsequent calculations.
4.3 Tax Calculation
The calculator comes with a pre-adjusted 5% tax rate. You can perform direct calculations for prices including or excluding tax.
- TAX+: Adds the pre-set tax rate to the displayed value.
- TAX-: Subtracts the pre-set tax rate from the displayed value.
4.4 Memory Functions
- M+: Adds the displayed value to the memory.
- M-: Subtracts the displayed value from the memory.
- MRC: Recalls the memory content (press once) or clears the memory (press twice).
4.5 Other Functions
- GT (Grand Total): Displays the grand total of all calculations performed since the last GT clear.
- MU (Mark-Up): Calculates mark-up and mark-down percentages.
- % (Percentage): Used for percentage calculations.
- √ (Square Root): Calculates the square root of the displayed number.
- 3-Key Rollover: Ensures that keystrokes are not lost during high-speed input, improving accuracy.
- Silent Touch Keys: Designed for quiet operation, reducing noise during use.
- Function Command Signs: Indicators on the display show the current operation being performed.
5. Maintenance
5.1 Cleaning
To clean the calculator, wipe it gently with a soft, dry cloth. Do not use abrasive cleaners, solvents, or excessive moisture, as these can damage the display or internal components.
5.2 Battery Replacement
When the display becomes dim or unresponsive in low light, it may be time to replace the battery. Refer to the battery compartment on the back of the calculator for instructions on how to open it and replace the battery. Ensure the calculator is powered off before replacing the battery.
5.3 Storage
Store the calculator in a cool, dry place away from direct sunlight and extreme temperatures. The anti-slip structure helps keep it stable on your desk.
6. Troubleshooting
6.1 Display Issues
- Dim Display: Ensure the calculator is in a well-lit area for solar power, or replace the battery if necessary.
- No Display: Press the AC/ON button. If still no display, check battery installation or replace the battery.
6.2 Calculation Errors
- Incorrect Results: Utilize the 300-step check and correct function (RECHECK, BACK, FORWARD, CORRECT buttons) to review your input and make corrections.
- Unexpected Behavior: Clear all calculations and memory by pressing AC/ON. If the issue persists, remove and reinsert the battery.
7. Specifications
| Feature | Detail |
|---|---|
| Manufacturer | Casio |
| Brand | Casio |
| Model Number | DS-1JT |
| Product Dimensions | 24 x 16 x 0.25 cm |
| Item Weight | 305 g |
| Color | Black, Gray |
| Material Type | Plastic |
| Number of Items | 1 |
| Power Source | Battery (1 required, included), Solar |
| Display Type | LCD |
| Compatible Devices | For single use |
8. Warranty and Support
For warranty information and customer support, please refer to the documentation included with your purchase or visit the official Casio website. Keep your proof of purchase for any warranty claims.





