---
product_id: 605894120
title: "FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students"
brand: "cliunt"
price: "€ 51.13"
currency: EUR
in_stock: true
reviews_count: 8
category: "Cliunt"
url: https://www.desertcart.gr/products/605894120-fx-991ex-scientific-calculator-engineering-scientific-calculator-with-552-functions
store_origin: GR
region: Greece
---

# High-res natural textbook display 552 versatile functions Dual solar + battery power FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students

**Brand:** cliunt
**Price:** € 51.13
**Availability:** ✅ In Stock

## Summary

> 📐 Elevate your calculations — because precision is the new power move.

## Quick Answers

- **What is this?** FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students by cliunt
- **How much does it cost?** € 51.13 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.gr](https://www.desertcart.gr/products/605894120-fx-991ex-scientific-calculator-engineering-scientific-calculator-with-552-functions)

## Best For

- cliunt enthusiasts

## Why This Product

- Trusted cliunt brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Unstoppable Power:** Dual solar and replaceable battery ensure your calculator never quits on you, anytime, anywhere.
- • **Compact & Portable:** Lightweight 170g design with sliding hard case fits perfectly in your bag for on-the-go productivity.
- • **Crystal Clear Visualization:** High-resolution LCD with natural textbook display makes complex formulas and graphs effortlessly readable.
- • **Master Complex Calculations:** 552 built-in functions covering algebra, calculus, stats & more for every academic challenge.
- • **Exam-Ready & Student Approved:** Trusted by students from middle school to college for reliable, intuitive use during exams and study sessions.

## Overview

The CLIUNT FX-991EX is a professional-grade scientific calculator featuring 552 functions, dual solar and battery power for uninterrupted use, and a high-resolution natural textbook display. Its compact, lightweight design with a protective sliding case makes it ideal for students and professionals tackling complex math, engineering, and statistical problems with clarity and confidence.

## Description

CLIUNT FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students: desertcart.co.uk: Stationery & Office Supplies

Review: Good - Good value for money. Good quality compared to leading brand
Review: Excellent :) - Excellent calculator :) Easy to use with clear buttons :)

## Features

- 552 Functions: This advanced scientific calculator provides a total of 552 scientific functions, covering a wide range of mathematical operations, including basic calculations, algebra, fractions, derivatives, integrals, scientific functions and statistical calculations, etc., Engineering scientific calculator allowing you to handle complex calculations with ease calculation.
- Dual Power Supply Electronic Calculator: Solar panel + replaceable button battery, dual safe uninterruptible power supply, environmental protection and energy saving advantages, smooth use, long battery life, you can use scientific calculator anytime and anywhere without worrying about battery problems.
- High-Resolution Display: The high-resolution Lcd display scientific calculator can be used to view spreadsheets, calculations, and other data,scientific calculator ensuring that numbers, symbols, and graphs are displayed clearly and easy to read, engineering scientific calculator is especially useful when working with complex mathematical expressions and charts.
- Natural Textbook Display: The calculator features a natural textbook display that covers most of the scientific functions students from middle school to college need for use in courses and exams. Entering expressions, symbols and arithmetic operations in the same form as written in the textbook ,scientific calculator will help students view the calculation process and results, engineering scientific calculator making it easier for students to understand and verify calculations.
- Easy to Carry: The size of this scientific calculator is 16.5*8*1.5cm and the weight is 170g. The compact and lightweight design makes it easy to carry and use anywhere. Engineering scientific calculator is equipped with a sliding hard case for easy portability.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0CRZ4F1T2 |
| Best Sellers Rank | 36,006 in Stationery & Office Supplies ( See Top 100 in Stationery & Office Supplies ) 77 in Scientific Calculators |
| Guaranteed software updates until | unknown |
| Item model number | Scientific Calculator-1 |
| Manufacturer | CLIUNT |
| Product Dimensions | 16.5 x 8 x 0.1 cm; 160 g |

## Product Details

- **Brand:** CLIUNT
- **Calculator Type:** Engineering/Scientific
- **Colour:** Black/White
- **Display type:** LCD
- **Material:** Silicone
- **Model name:** Scientific Calculator
- **Number of batteries:** 1 CR2 batteries required.
- **Power source:** Solar Powered
- **Product dimensions:** 16.5L x 8W centimetres
- **Screen size:** 3.14 Inches

## Images

![FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students - Image 1](https://m.media-amazon.com/images/I/61-Ve91ZypL.jpg)
![FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students - Image 2](https://m.media-amazon.com/images/I/617ew1acJLL.jpg)
![FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students - Image 3](https://m.media-amazon.com/images/I/61BySLHEltL.jpg)
![FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students - Image 4](https://m.media-amazon.com/images/I/61J09ILbW3L.jpg)
![FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students - Image 5](https://m.media-amazon.com/images/I/61MQUXR-2SL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Good
*by A***R on 18 November 2024*

Good value for money. Good quality compared to leading brand

### ⭐⭐⭐⭐⭐ Excellent :)
*by M***T on 21 August 2024*

Excellent calculator :) Easy to use with clear buttons :)

### ⭐⭐⭐⭐ You've Got To Love the SLOVE! (Detailed Review)
*by T***R on 9 June 2024*

TL;DR Summary Review The CLIUNT TY-991EX is a suitable alternative to a similar model made by another more popular brand. On the plus side, it produces very reliable answers to the questions asked of it. On the negative side, it lacks the QR (graph creation) function, it can be quite slow with some calculations, and the buttons have a hard plastic feel to them. Nevertheless, this is an excellent value advanced scientific calculator, and well worth the money. Full Review. The CLIUNT TY-991EX, made by Shenzhen Tianyan Electronics in China, is designed to replicate a similarly-named 991EX calculator from another manufacturer in Japan which I shall refer to in this review by the secret name Cassiopeia to avoid mentioning it in any way. For those buyers already familiar with the Cassiopeia equivalent, it won’t take long to find your way around this model, although there are several differences which make it appear more than a little quirky. Let’s look first, then, at the buttons and their layout. REVIEW SECTION A: BUTTONS Cassiopeia – 4 metal buttons in the top row, 4 metal navigation cursor buttons. TY-991eX – 4 metallic plastic buttons in the top row, 4 metallic plastic navigation cursor buttons. Cassiopeia – 22 black buttons with white text, rounded rectangular, rounded convex surface TY-991EX – 22 black buttons with white text, octagonal, rounded convex surface Cassiopeia – 18 white buttons with black text, 2 blue buttons with white text, rounded rectangular, rounded concave surface TY-991EX – 18 white buttons with black text, 2 orange buttons with black text, octagonal, rounded concave surface Where To Find It: BUTTON MIGRATIONS AND NEW LABELLING (and “SLOVE”) NB. The Four-Column Table which follows may not render well in all browsers. Please copy the text that follows and adjust formatting if necessary. Cassiopeia Function Button Cassiopeia Position TY-991EX Equivalent New label (If any) Shift Top row, 1st Top row, 3rd Menu – Setup Top row, 3rd Second row, 3rd Function – Setup ON Top row, 4th Top row, 1st OPTN – QR Second row, 1st Second row, 4th MISC (no QR function) CALC – SOLVE/= Second row, 2nd Top row, 4th CALC/SLOVE = (all text above metallic button) Integral – Derivative / Colon Second row, 3rd Second row, 1st X – Series Summation Second row, 4th Second row, 2nd STO – RECALL Fifth row, 1st Fifth row, 3rd SetTo – RELOAD ENG – Complex Format Fifth row, 2nd Fifth row, 4th Left Parenthesis – Abs Fifth row, 3rd Fifth row, 1st Right Parenthesis – Comma / X Fifth row, 4th Fifth row, 2nd S<=>D Fifth row, 5th (No movement) CHG 7 – CONST 6th row, 1st (No movement) 7 – CONSTANT 8 - CONV 6th row, 2nd (No movement) 8 - CONVERSION REVIEW SECTION B: Physical Constants All the values I have sampled have displayed the same value as their equivalents on the Cassiopeia model. However, care must be taken to round the quoted values to no more than about 4 or 5 significant figures, since the accuracy of the stated values does not generally correspond to their current published values. Some examples follow, with the 2022 CODATA Recommended Values of the Fundamental Physical Constants, National Institute of Standards and Technology, given in square brackets for comparison. As usual, EXP is used as shorthand for “x 10 to the power of” Planck’s constant h = 6.626 069 57 EXP -34 [6.626 070 15 EXP -34] Boltzmann's constant k = 1.380 648 8 EXP -23 [1.380 649 EXP -23] Avogadro’s constant NA = 6.022 141 29 EXP 23 [6.022 140 76 EXP 23] The “Big G” Gravitational constant G = 6.673 84 EXP -11 [6.674 30 EXP -11] Electron charge e = 1.602 176 565 EXP -19 [1.602 176 634 EXP -19] REVIEW SECTION C: Accuracy of Answers 1. Mike Sebastian’s "Forensic Formula" INPUT : arc sin( arc cos( arc tan( tan( cos( sin( 9)))))) in degree mode Cassiopeia answer = 9.000000007 TY-991EX answer = 8.999999998 Result: TY-991EX wins 2. Powers of roots INPUT: ( SQRT( SQRT( SQRT( SQRT( SQRT( Pi ))))))^ 32 Cassiopeia answer = 3.141592654 TY-991EX answer = Pi Result: TY-991EX wins 3. Inverse Normal calculation INPUT: For X~N(0,1) find x s.t. P(X<x)=0.6 Cassiopeia answer = 0.2533471219 TY-991EX answer = 0.2533470931 Online answer from Desmos = 0.253347103136 Result: TY-991EX wins 4. Stored value of Pi INPUT: Pi – 3.1415926 Cassiopeia answer = 5.35898 EXP -8 TY-991EX answer = 5.3589793 EXP -8 Result: TY-991EX wins 5. Large Binomial X~(113, 0.13) INPUT: P(X = 70) Cassiopeia answer = 7.317250193 EXP -34 TY-991EX answer = 7.317250236 EXP -34 Online answer from Desmos = 7.3172502364 EXP −34 Result: TY-991EX wins REVIEW SECTION D: Speed of Calculation – compared with Cassiopeia Models 991EX and 991CW TEST 1 – Non-Converging Newton-Raphson The equation x^3 + 1 = 0 has a horizontal tangent at x = 0 so this is the worst possible ‘seed’ for Newton-Raphson. Using SOLVE (or “SLOVE”) with a starting x value of 0, will take a while to solve because the algorithm must first venture slightly left or right of zero in order to find a seed which will lead to convergence. Cassiopeia Model 991CW gives x = -1 in under 1 second. Cassiopeia Model 991EX requires a second ‘Continue’ to reach x = -1 TY-991EX reaches x= -1 after about 3 seconds Conclusion: TY-991EX is slow, but it gets there. TEST 2 – No Solution The equation x^2 + 1 = 0 has no solution. Let’s try to SOLVE / SLOVE this with seed x = 0. Cassiopeia Model 991CW gives "Cannot Solve” in 2 seconds. Cassiopeia Model 991EX gives "Cannot Solve” in 3 seconds. TY-991EX gives "Cannot Solve” in 23 seconds. Conclusion: TY-991EX is VERY slow, but it gets there. TEST 3 – Cycling Solutions (Period 2) The equation x^3 – 2x + 2 = 0 has one real solution around x = -1.8, but the Newton-Raphson process starting at x = 1 cycles between two values (0 and 1). Cassiopeia Model 991CW gives "Continue” in 3 seconds then “Cannot solve” 3 seconds later. Cassiopeia Model 991EX gives "Continue” in 3 seconds then “Cannot solve” 4 seconds later. TY-991EX gives x = -1.769 (etc) in 2 seconds Conclusion: TY-991EX is the winner here. TEST 4 – Simultaneous Equations in 4 Unknowns, Real Solution This example omits one variable in each equation, so translates to having coefficients simply of 1 and zero. The solutions are integers. x1 + x2 + x3 = 75 x1 + x2 + x4 = 80 x1 + x3 + x4 = 75 x2 + x3 + x4 = 70 Cassiopeia Model 991CW solves instantly Cassiopeia Model 991EX solves instantly TY-991EX solves instantly Conclusion: No noticeable difference in solution speeds. TEST 5 – 4 x 4 Matrix Inversion of an invertible matrix, Matrix A as below: 2 0 0 -2 1 3 1 0 0 0 -3 0 1 2 0 0 Cassiopeia Model 991CW solves instantly Cassiopeia Model 991EX solves instantly TY-991EX solves instantly Conclusion: No noticeable difference in solution speeds. TEST 6 – Binomial with very large number of trials While we typically approximate Binomial to Normal once n > 30 and np > 5, it is fun to push calculators to find exact values for large n. For this test, we are going to calculate: P (X < 37) for X~N (144,0.2) Note that individual Binomial probabilities such as P(X = 37) become vanishingly small as n increases (see Accuracy Test above), so we use an inequality, requiring the calculator to find the sum of all these very small values. Cassiopeia Model 991CW solves instantly Cassiopeia Model 991EX solves instantly TY-991EX solves in under a second Conclusion: No appreciable difference in solution speeds. TEST 7 – Numerical Integration under the Gaussian (Normal) Curve For unit standard deviation and zero mean, the equation of the Normal curve simplifies to: F(x) = (2 Pi)^(-0.5) e^(-0.5 x^2) We can check the “68, 95, 99.8” rule by finding the area between ±2 standard deviations of the mean, i.e. between –2 and 2. Cassiopeia Model 991CW takes 4 seconds Cassiopeia Model 991EX takes 1.5 seconds TY-991EX takes 9 seconds Conclusion: The TY-991EX is VERY slow on this one. APPENDIX: DIAGNOSTIC MODE (Courtesy of Guy Macon under Creative Commons Licence) As with the Cassiopeia 991EX, one enters Diagnostic Mode by holding Shift-7 then tapping ON. As with anything else involving the ON key, it doesn't matter what the calculator is doing and it doesn't matter whether the calculator is on or off. You should see: DIAGNOSTIC Press AC When you see the above, you have 15 seconds to press a key to start the diagnostics. If you are too slow it will go to the normal flashing cursor. The only keys that do anything are ON (ON always works the same no matter what), AC, 8, and 9. AC simply exits the diagnostics and brings up the flashing cursor. 8 and 9 are the actual tests. On the Cassiopeia, there is an additional series of tests under 6, but this is not the case with the TY-991EX, which has only two test modes, under 8 and 9. Test 8 (SHIFT+7, ON, 8): Pressing 8 should display the following: [1] KI1 KO1 [SHIFT] KI8 KO1 [5] KI2 KO2 [9] KI3 KO3 [)] KI4 KO4 [log] KI6 KO5 [logab] KI7 KO6 [0] KI5 KO7 "[1] KI1 KO1" means "pressing the 1 key will test the connection between key input #1 and key output #1 on the chip". As you press each key, that line on the display should highlight/change to reverse (light text on a dark background). When it asks you to press the "logab" key it means the x directly below the ALPHA key. This mislabelling may mean that the diagnostic software came originally from a different model. After you highlight the last line, this should instantly result in this display: Battery Model OK! There appears to be no way to test the Solar panel, unlike the Cassiopeia diagnostics. AC should bring you back to the flashing cursor. Test 9 (SHIFT+7, ON, 9): This is the test that is used at the factory to test the calculator after it is manufactured. Many of the tests are the same as the ones above, but this time you have to do all of them to finish. Pressing 9 should display the following: 8888888888888888 8.888888889x10^15 This appears to be a test to see if all the segments in an eight-segment display turn on, but this calculator uses a matrix display, so this may be a sign that the same diagnostics are used on many different models. Press SHIFT to enter the Display test. Press SHIFT four more times to enter the Version test. CY-235 VerA Press AC Press AC to enter the key test. The Sequence of Key Presses must be done in this order: Shift, ALPHA, UP, RIGHT, Function, Misc, which takes the count up to 06. I could find no more keys to take this count higher. On the Cassiopeia, each key in turn increments the count. Press ON to exit the testing.

## Frequently Bought Together

- CLIUNT FX-991EX Scientific Calculator, Engineering Scientific Calculator With 552 Functions, Lcd Display Scientific Calculators for School Students
- Pearson Edexcel AS and A level Mathematics Pure Mathematics Year 1/AS Textbook + e-book (A level Maths and Further Maths 2017)
- Edexcel AS and A level Mathematics Statistics & Mechanics Year 1/AS Textbook + e-book

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*Product available on Desertcart Greece*
*Store origin: GR*
*Last updated: 2026-01-29*