In Chicago, I’ve spent years testing, reviewing, and teaching with scientific calculators, from the old Casio FX-82 to the newest FX-991EX. As a calculator expert who often mentors engineering and science students, I’ve seen how the right calculator can turn confusion into clarity. The Casio FX-991EX surprised me with its balance of speed, precision, and design. It’s small, yet powerful enough to handle serious math without the bulk of a graphing model.

The Casio FX-991EX Advanced Scientific Calculator is well-known as one of the top non-graphing scientific calculators you can buy, appreciated for its wide range of features, clear “Natural Textbook Display,” and quick performance. It is perfect for students from high school to college engineering programs and is allowed in most standardised tests.

Still, even a trusted tool like this has quirks that need mentioning. I’ll share what I loved, where I struggled, and how it could be better, so you’ll know if it fits your study or work routine.

Expert and User Review Summary

We tested the Casio FX-991EX (from the ClassWiz series) regularly gets excellent reviews from both professionals (like a former Head of Mathematics) and everyday users for its effectiveness and good value. This model is a big improvement over the older FX-991ES Plus, offering quicker performance and additional features, all in a slim design that works with both solar power and batteries.

Pros and Cons

Pros:

Clear Display: It has a display that is four times sharper than that of the 991ES Plus, making it possible to see math expressions just like they look in textbooks (Natural Textbook Display).

Wide Range of Functions: It includes 552 functions, allowing for complex calculations involving matrices (up to 4×4), vectors, integration, differentiation, and statistics (such as binomial, Poisson, and Normal distributions), solving simultaneous equations (with up to four unknowns), and working with polynomial inequalities.

Speed: This calculator is significantly quicker than older versions, which is very helpful during tests.

Dual Power: It can run on solar energy and has a backup LR44 battery, ensuring it works well in different lighting situations.

Easy-to-Use Interface: It has a simple icon-based menu and uses clear English messages, making it easier for users to find and access functions.

QR Code Feature: A standout feature that creates a QR code for an equation, which can be scanned with a smartphone to see graphical images on a bigger screen.

Cons:

Learning Time: Because of its many features, new users might need to watch videos online or read the guide to fully understand how to use everything.

No Saved History: Once you turn off the calculator, it erases the history of what you did, so you can’t go back and change a previous answer after the ANS (answer) is shown.

Minor Missing Feature: One user mentioned that the calculator does not include the “recurring” symbol for decimals (like that of 1/3), which is a small feature that older models had.

Quality Feel: Although it is sturdy, some users feel that the slim and light plastic design seems less “heavy-duty” compared to bulkier older models.

Is Casio FX-991EX Advanced Scientific Calculator Good?

Yes, this calculator is a reliable powerhouse for students, engineers, and technical professionals. During my testing sessions, I used it to solve matrix operations, complex number equations, and integration problems. The Natural Textbook Display made everything appear just like it would in a real textbook, which made checking answers easier and faster.

I appreciated how quickly it handled logarithmic and trigonometric equations, especially under pressure during live calculations. The 417 built-in functions, dual power (solar + battery), and durable hard case make it a great fit for everyday academic and professional use.

When I compared it to the older FX-991ES Plus 2nd Edition, I noticed the EX version felt quicker and smoother, almost like going from a regular sedan to a hybrid sports model.

What I Like

• High Functionality with Easy Interface:
  It covers everything from statistics to calculus without overwhelming the user. I could jump between vector and matrix modes with no lag.
• Natural Textbook Display (NTD):
  The NTD layout helps visualize equations exactly as printed in books. It’s a major plus for high-school and college students.
• Dual Power and Long Battery Life:
  The combination of solar and battery power means I never worry about it dying mid-exam.
• Durability and Design:
  The keys have a soft tactile feel, and the slide-on case protects it well. I’ve dropped it twice, and it didn’t even flinch, proof of Casio’s sturdy build.
• Trusted Japanese Quality:
  It follows ISO 14001 and RoHS compliance standards, which means strong build quality and eco-friendly manufacturing.

What Could Be Better

Amazing item. Quality is good. Highly recommended if you want to do calculations. It’s very good with the numbering. I am an engineering student. Everything is working fine for me. Remember, not for graphing. If you are looking to graph, this is not the product. Otherwise amazing. Highly recommended. And very easy to use. –MUSA MD FAHIM ISLAM

• No Backlight:
  In low-light conditions, visibility drops. A subtle backlight would make it perfect for late-night study sessions.
• Limited Programming Capability:
  It’s non-programmable by design, which is great for exams but limits advanced automation for research users.
• Learning Curve for Beginners:
  While intuitive, the function menus can feel dense at first. A quick-start guide with visual shortcuts would help newcomers get comfortable faster.

How We Tested

This calculator is amazing. It is able to show equations in a textbook format. Perfect for any STEM class that is math-heavy. The gadget also has a variety of conversions and modes that make it perfect for students and professionals alike. – Joshua Hernandez

• Ran daily engineering and math problems, including integration, differentiation, and vector analysis.
• Compared calculation speed with Casio FX-991ES Plus 2nd Edition and TI-36X Pro.
• Tested display clarity under different lighting conditions.
• Evaluated button responsiveness after 10 hours of continuous use.
• Measured durability with casual drop and stress tests, no performance issues detected.

Each test reinforced how fast, reliable, and exam-friendly this model is.

Our Recommendation

If you’re a student, engineer, or data-driven professional, the Casio FX-991EX is an excellent choice. It’s ideal for high-school AP courses, college engineering programs, and professional fields that need accurate, portable computation.

For U.S. buyers, this calculator aligns well with college entrance exam standards and engineering accreditation rules, making it a safe, compliant choice for both academic and professional environments.

However, if you prefer programmable or graphing features, explore Casio’s ClassWiz or TI-84 Plus series.

Casio FX-991EX Advanced Scientific Calculator Tested Review

As a calculator expert with over a decade of experience testing, reviewing, and teaching with advanced models, I’ve used nearly every Casio scientific calculator that’s hit the market. From the FX-82MS to the FX-991ES Plus, I’ve seen how Casio continues to refine speed, layout, and usability for students and professionals alike.

What I struggled with, however, was how most calculators either feel too basic or too bulky. The Casio FX-991EX bridges that gap beautifully, but not without a few quirks worth noting.

Even as an expert, I’ve faced moments when I wanted smoother navigation or a little backlight support during late study sessions. Still, this calculator manages to stand tall as one of the best in its class.

Hands-On Experience

Using the Casio FX-991EX daily in real-world scenarios, from solving matrix operations to running calculus problems, has given me a genuine feel for its strengths and limits. It handles trigonometric, logarithmic, and statistical functions smoothly, and the Natural Textbook Display (NTD) makes every equation look like it came straight out of a printed math book.

This feature alone cuts down on mistakes because what you see is exactly how you’d write it by hand. The 417 functions, solar-plus-battery power, and sleek protective hard case give it the right mix of practicality and reliability.

Problems I Faced

Despite the positives, there were a few pain points worth sharing.

• The lack of backlight made it difficult to use under dim light, especially during late-night tutoring sessions.
• The menu navigation can feel a bit deep at times, some functions are buried behind multiple key presses.
• Its non-programmable design, while exam-safe, limits advanced users who want to automate formulas or store scripts.

Solution (In Short)

Casio could easily fix these small issues in the next edition by adding a soft backlight and simplifying the menu structure. A quick-access mode or customizable shortcuts could make a huge difference for advanced users.

That said, for most students and professionals, these are minor trade-offs for what you get, speed, reliability, and accuracy in a slim, portable build.

Alternative Options: Casio

As a calculator expert, I have used several brands in the last 22 years. I have a lot of respect for Casio because they offer great value and features. The Casio FX-991EX Advanced Scientific Calculator is a powerhouse. It is famous for its high-resolution screen and deep functions. Still, it is smart to see how it compares to other top scientific models.

Advanced Scientific Calculator

Choosing an advanced scientific calculator is key to high school and college success. You need one that handles complex numbers, matrices, and vectors. I have found that a good display, like the one on the Casio FX-991EX, makes a big difference. It shows formulas just like they look in a textbook.

Feature	Casio FX-991EX	Casio FX-991ES Plus-2nd	Texas Instruments TI-36X Pro
Display	High-Res Natural Textbook	Natural Textbook	Multi-view
Functions	552	417	4 lines
Power Source	Solar and Battery	Solar and Battery	Solar and Battery
Key Advantage	Spreadsheet, QR code function	Simple to use, affordable	Simple layout, clear display
My Rating (Out of 10)	9.5	8.5	8.0

The Casio FX-991EX Advanced Scientific Calculator is the clear winner for features. The FX-991ES Plus-2nd is a reliable and cheaper version. The TI-36X Pro is a sturdy model with a great reputation.

Scientific Calculator

When I look at a basic scientific calculator, I check for the number of functions and ease of use. I often advise students to get the most advanced one they can afford, like the Casio FX-991EX. It means they will not need to buy a new one later on. The ability to solve equations right on the calculator is a huge time saver.

Feature	Casio FX-991EX	Canon F-789SGA	Sharp EL-W516XBSL
Matrix Size	Up to 4×4	Up to 4×4	Up to 4×4
Equation Solver	Yes (4 simultaneous, 4 polynomial)	Yes (4 simultaneous, 4 polynomial)	Yes (4 simultaneous, 4 polynomial)
Display Lines	4-6 lines	4 lines	4 lines
Best Feature	Superior display, higher functions	Great build quality, simple to use	WriteView display, deep functions
My Rating (Out of 10)	9.5	7.5	8.0

The Casio FX-991EX gives you the best display and the most functions. The Canon is a solid choice for a simple scientific calculator. The Sharp model has a good display and plenty of power for advanced math.

Engineering Scientific Calculator

An engineering scientific calculator must handle difficult problems like integration and differentiation. The Casio FX-991EX is ideal for engineering students. Its ability to handle vector and matrix calculations is a must-have for those courses. This powerful model helps me check my work quickly.

Feature	Casio FX-991EX	HP 35s	Casio FX-991ES Plus-2nd
Vector/Matrix	Yes	No	Yes
Complex Numbers	Yes	Yes	Yes
Entry System	Algebraic	Algebraic and RPN	Algebraic
Best Feature	Spreadsheet mode, high-res screen	RPN option, great for exams	Cost-effective, very common
My Rating (Out of 10)	9.5	8.0	8.5

The Casio FX-991EX is the top choice for modern engineering students. The HP 35s is a classic choice for those who prefer RPN. The older Casio FX-991ES Plus-2nd is a reliable and solid backup.

Final Verdict

The Casio FX-991EX Advanced Scientific Calculator is a near-perfect blend of power and simplicity. It’s fast, intuitive, and built with the precision you expect from Casio’s Japanese craftsmanship.

If you’re a student, engineer, or science enthusiast who needs an exam-approved calculator that performs like a premium model without the learning curve of a graphing calculator, this is the one to get.

For me, it scored a solid 9.5/10 for reliability, usability, and accuracy.
Casio has once again proven that high performance doesn’t have to come with high complexity.

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