# Scientific Calculator Casio FX-991DE X Black Battery Solar

**URL:** https://aio.lv/en/product--casio-fx-991dex-k--4147073
**Data updated:** 2026-01-13 21:19 (EET)
**Category:** Calculators
**Manufacturer:** CASIO
**Manufacturer code:** FX-991DEX-K
**EAN:** 4549526611865
**Warranty:** 2 Years
**Availability:** Available for order
**Price:** 41.49 €
**Prices and availability valid until:** 2026-07-14 23:59
**Price without VAT (21%):** 34.29 EUR
**Can be purchased by legal entities:** Yes (invoice)
**Buy:** https://aio.lv/en/product--casio-fx-991dex-k--4147073

## Delivery options

| Delivery method | Delivery time | Cost |
|---|---|---|
| Office pickup (2b. Kengaraga str., Riga, Latvia, LV-1063) | 01.07.2026 | free |
| Pickup points | 06.07.2026 | 1.99 EUR |
| Courier delivery to door | 06.07.2026 | 4.99 EUR |

## Summary description

The Casio FX-991DE X is a desktop scientific calculator with a sleek black design. It operates on both battery and solar power, ensuring versatility in various environments. This calculator is ideal for students and professionals, offering a wide range of functions for complex calculations, making it a reliable tool for academic and professional use.

## Long description

The Casio FX-991DE X Black Battery Solar is a scientific desktop calculator designed for accurate numeric and symbolic computation in academic and professional settings. It features a clear display and a durable black housing, with hybrid power through battery and solar cells to maintain operation in varied lighting conditions. The instrument provides a broad set of mathematical and statistical functions suited to algebra, calculus, engineering and science tasks.
Advantages
This calculator combines battery and solar power for reliable use without frequent interruptions. The layout and display support multi-line expressions, improving the readability of equations and results. It offers an extensive function set that covers fractions, matrices, complex numbers, regression and integral/derivative calculations, enabling efficient handling of advanced problems. The sturdy casing and tactile keys are intended to withstand regular classroom or office use.
Suitable for
High school and university mathematics and physics courses
Engineering problem solving and technical studies
Statistical analysis and data processing tasks
Laboratory calculations and applied science assignments
Key specifications
Power source: battery with solar assist for extended operation
Display: multi-line screen for expressions and results
Functions: scientific, statistical, matrix, complex number operations, integrals and derivatives
Keyboard: tactile, durable keys for frequent input
Design: compact desktop form factor with black housing
How to use
Turn the calculator on using the power key and ensure the solar panel receives sufficient light for optimal operation alongside the battery. Enter expressions using the multi-line display to build complex calculations step by step; use the dedicated function keys to access trigonometric, logarithmic, matrix and statistical modes. Confirm entries with the equals key and navigate previous results or expression history where supported. Switch between degrees and radians as needed for angle calculations and select appropriate modes for complex or matrix operations before inputting data.
Usage recommendations
For consistent performance, store the calculator away from extreme temperatures and replace the battery when the display dims despite adequate light. Use the manual to identify function key sequences for matrix and symbolic operations and practice common workflows to increase speed during exams or timed tasks.

## Specifications

| Feature | Value |
|---|---|
| Type | Scientific |
| Weight | 0.09 kg |
| Form factor | Desktop |
| Battery type | LR44 |
| Number of batteries supported | 1 |
| Power source | Battery/Solar |
| Height | 11.1 mm |
| Display resolution | 192 x 63 |
| Width | 77 mm |
| Depth | 165.5 mm |
| Backlight display | No |
| Product colour | Black |
| Control type | Buttons |
| Second display | No |
| Display tilting | No |
| Display type | Dot-matrix |
| Keys quantity | 50 keys |
| Cover | Yes |

## FAQ

### How much does the Scientific Calculator Casio FX-991DE X cost, and is it available for purchase?

The price is 41.49 € (valid at the time of publication and already includes all taxes). The item is available for order — 4 pcs. are in stock, and you can place your purchase right now with delivery across Latvia and Europe or choose pickup at the Riga collection point. We offer favorable purchase terms, including the option to split the payment into convenient monthly installments. Availability and price are updated in real time, so we recommend placing your order in advance.

### If I order this product today, when will I receive my order?

If you place your order today, delivery will be as fast and convenient as possible. You will be able to pick up your order on 01.07.2026 at the Riga pickup point or choose delivery across Latvia and Europe. We carefully inspect every purchase and pack it securely for safe transportation.

### What payment options are available?

AiO.lv offers several payment methods: Bank transfer, Bank cards on-line, Apple Pay, Google Pay. All transactions are 100% secure and encrypted.

### Can this product be purchased for a company (with VAT)?

Yes. AiO.lv works with legal entities in Latvia and across Europe. The product price already includes VAT. For certain product categories, as well as for companies from other EU countries with a valid VAT number, a 0% VAT rate may apply. We issue the invoice immediately after the order is placed, support electronic BIS invoices, and automatically generate all necessary accounting documents. You can complete the purchase for a company online — simply select the company profile and choose bank transfer as the payment method during checkout.

### What is the warranty period?

All CASIO products come with an official 2 Years warranty. It covers all manufacturing defects and malfunctions that may occur during use. The warranty is valid at all authorized CASIO service centers and through AiO.lv

### Can the product be returned after purchase?

Yes, you can return the product within 14 days of purchase if you bought it as a consumer (not a legal entity). Returns are possible without giving any reason — the main condition is that the product retains its original appearance and full set of accessories. We will make the process as simple and convenient as possible: just contact our customer support team, and we will help you arrange the return.

### Where should I contact for warranty service?

For warranty-related questions you can contact the AiO.lv (SIA VSPRO) customer support team. More information about warranty service: https://aio.lv/en/warranty

## Image

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