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Casio FX High Performance Calculator

By Kathleen Cantor, 10 Aug 2021

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Casio FX calculators are well known for their quality and high performance. But if you want a Casio calculator that really earns its keep, the FX-991EX is as advanced as it can get. Between stellar features and the ability to use it in most regional and nationwide exams, like the SATs, it's a great tool for both high school and introductory-level college courses.

Let's take a closer look at the FX-991EX compared to Casio's other high-performance calculators.

What Are the Key Features of a Casio FX?

The Casio FX belongs to the ClassWiz series. These calculators have a high-resolution and high-pixel LC display. This is a greater resolution than those calculators in the FX-ES Plus series. The Casio ClassWiz series also boasts faster processors and double the memory size.

Where the Casio FX-991EX Stands Out

Considering that, the improved features of the FX series make the Casio FX-991EX's features all the more powerful. The calculator can perform basic mathematical functions, numeric integration/differentiation, scientific and statistical calculations.

In addition to the basics, this Casio FX can solve more advanced equations:

  • Polynomials up to degree 4
  • Integration (finding the area under curves) or differentiation
  • Boolean logic

You can also calculate more rows of data in a table.


From a design standpoint, it is visually more pleasing than the other calculators in the FX series. The keyboard on this model is outstanding in both feel and key action, while the display is easy to read considering that it's not backlit.


Scientific calculators are significantly more inexpensive than graphing calculators—so you don't have to worry about paying $100 for a calculator. On average, you could find this model for $18-$30, making it a great option for students who only need a scientific calculator for one class or exam.

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Power and Battery Life

This calculator is fast, earning its title as a high-performance calculator. It does most things instantly. The calculator mostly uses solar power. You can tell when the solar battery kicks in by the sun icon on the screen. If the calculator's light is too dim, the LR44 battery will kick in and take over. The good thing about LR44 is that they're easy to find. They're cheap, too!

User Experience

Like all Casio FX calculators, the FX-991EX comes with clear and detailed instructions. This will help you figure out how to adjust the settings in a way that makes you comfortable to work with them. Further, the instructions show how to use all the extensive functions. That said, there is a learning curve.

What Makes This Casio FX Better Than Older Casios?

Casio is a great brand for scientific calculators, so you should be okay if you have a model a few years older than the more recent ones. However, compared to the FX-991ES PLUS (one of the higher-rated older models), the FX-991EX includes more features and a sleek new user interface closer to common math textbooks.

The calculator also has more numbers, like Hex and Octal. In addition, the Matrix, Vector, and equation solving are all a bit smoother than the FX-991ES PLUS. Casio even updated the calculator to include a spreadsheet function.

It may be worth the update.

The Pros and Cons of Buying a Casio FX

So let's review the pros and cons.


  • Powerful hardware
  • Long battery life
  • Versatile functions with some advanced calculations
  • Affordable

This calculator is quite powerful in terms of what it's able to do and is usable both in high school and college exams. It also looks great. It has the design of more expensive models but at a lower price. It's durable and light and comes with a stylish slim white case. Although you cannot program your calculator, it can calculate in hexadecimal and binary.


This calculator does not have CAS, which stands for "Computer Algebra System." Still, exam proctors do not permit calculators with CAS in most exams. The buttons' background is a textured finish which can make the dark labels difficult to read at times. Also, the Casio FX-991EX matrices only go up to 4x4, and it isn't programmable.

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Is It Worth It?

Overall, you can't lose with a Casio FX. In the world of scientific calculators, the FX series is a strong contender. Casio has spent years refining the way their FX calculators work, and it clearly shows.

If you want a smooth sailing math—and even science—experience, this calculator is for you. The Casio FX-991EX is readily available on Amazon for under $30 if you want a speedy delivery to your doorstep.

Although $30 can sound like a lot, keep in mind some of the best calculators can be over $100. Plus, this Casio FX has everything you could wish for in terms of functions, usability, and looks. Casio FX high-performance calculators are definitely the way to go.


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