Sunday, November 1, 2015

Casio fx-991EX Classwiz Review

Casio fx-991EX Classwiz Review

Casio FX-991EX 

The next incarnation of the fx-991 line of Casio calculators is the fx-991 EX. 

Cost:  Approximately $20 - $21 USD
Availability:  Online. 
Power:  Solar + 1 Battery LR 44

The general features of the fx-991 EX Classwiz

* Calculation Mode:  A choice of either linear or textbook input/output
* Prime Factorization of integers
* Calculus functions include:  numeric derivative, definite integrals, summation
* Solver
* Complex numbers (arithmetic, polar/rectangular conversions only).  The [ENG] key works as the imaginary unit (i, shift for angle).
* Base calculations:  Binary, Octal, Decimal, Hexadecimal; with the usual logic operations and, or, not (1’s compliment), xor, xnor, neg (2’s compliment).  In binary mode, 32 bits are displayed, with the left most bit as the sign bit (0 for positive, 1 for negative).  This is double the 16 bits of previous models. 
*  Up to 4 x 4 linear systems and 4th order polynomials can be solved through the Equation Mode (up from 3 x 3 and 3rd order from previous Casio models, respectively).
* Statistics regression models include linear, quadratic, logarithmic, exponential, power (a*b^x and a*x^b), and inverse.  (see the QR section later)
* Tables of two functions, f(x) and g(x), of which functions can be graphed (see the QR section later).
* Distribution Mode:  Normal curve (and inverse), binomial, Poisson. 
* Other modes include inequality testing, basic vector mode, and ratio solving mode.
* 10 variables (A, B, C, D, E, F, x, y, M), 47 constants, and conversions. 
There are four features that make the fx-991 EX Classwiz stand out: 

* A fast processor, which reduce waiting time for long calculations.  In the few short tests I did, I am impressed.

The screen

* The screen resembles the Casio Prizm graphing calculator screen.  According to Casio, the screen has a 192 x 63 pixel resolution.  Even the mode menu represents a matrix of graphic icons similar to the Casio graphing calculator counterparts.

The fx-991EX Classwiz Menu

* Spreadsheet
* The ability to capture screen shots and get graphs of functions and statistics with the QR codes.

I will talk about the Spreadsheet and QR Codes in later sections.


Vs. Canon F-792GA

* The Canon F-792SGA’s binary mode also has 32 bits.  To cycle through bits (8 at a time), press [Shift] [ ln ] (<Blk).   The nice thing about the Casio fx-991EX Classwiz is that all 32 bits are displayed at once!
* Similarly, Casio (fx-991EX Classwiz) now joins Canon (F-792SGA) in the order of which linear systems and polynomials can be solved (4).   
* Also, like the F-792SGA, the fx-991EX Classwiz has an Options button that organizes many functions that are not on the keyboard. (Canon has [Apps], Casio has [OPTN])

They Didn’t Make It

* The functions that did not make it from the fx-115 ES Plus to the fx-991EX Classwiz:  GCD, LCM, Int (integer part), Intg (integer part), and product (Π).

The Keyboard of the fx-991EX Classwiz

* The fx-991EX Classwiz has a dedicated [ x ] key, eliminating the need to press [ ALPHA ], [ ) ] (x). 
* The Store and Recall have been switched.  Previously, recall was primary function and store was the shifted function.  For the fx-991EX Classwiz, the store is the primary function and recall is the shifted function. 

The fx-991EX Classwiz has two exciting firsts for solar scientific calculators:  Spreadsheet and Graphing (via QR codes read through your smart phone/iPod Touch/tablets)


Spreadsheet of the fx-991EX Classwiz
The spreadsheet is a basic spreadsheet that contains 225 cells (45 rows and 5 columns).  While the ability to name cells and ranges are not present (hopefully the next version will provide such ability), classical spreadsheet analysis is present: Sum, Minimum, Maximum, Average (Mean), and filling cells with a certain value.  We also have the option of using relative or absolute cell references.   In spreadsheet mode, pretty much every function is accessed through the Option menu.   The fx-991 EX Classwiz allocates 1,700 bytes for the spreadsheet function (I think this is exclusive memory set aside for this mode).

QR Codes:  Displaying Results and Graphs

QR demonstration

One of my dream capabilities is for a solar calculator with that can graph functions.   The fx-991 EX Classwiz takes a step towards that.  While the calculator does not display graphs itself, it can send information to a smart phone app to display graphs. 

What is needed is a Casio EDU+ app, which is available for the iOS and Android.   Your device needs to be connected to the internet. 

How to use to generate QR code:

1.  Get to the screen you want to capture.  For graphs, capture a table from Table mode or Statistics mode.
2. Press [SHIFT] [OPTN] (QR).  A QR code (a box) is generated.
3. On your device, run the Casio EDU+ app and choose QR code.  You are prompted on the app to point the camera at the calculator.  Adjust the calculator and/or app as necessary.  It may require patience and practice.
4. At success, you will be notified that by the app.  The results will be shown on the device’s browser.   The website is run by Casio and ke!san.  ( 

Note:  The Start and End represents the Xmin and Xmax, respectively of the graph.  Choose an appropriate Step.  For a wide domain, choose a large Step, as the Table mode is limited to display 45 rows (for one function) or 30 rows (for two functions).

Results can be emailed, saved, or put into Latex code. 

Final Thoughts

I am excited in the direction Casio is going with their scientific calculator line.  Is it worth getting?  Sure, especially if you like the functions that the fx-991EX Classwiz has to offer.  I am happy with the introductory spreadsheet mode, crisp display, and the fast processor.  The QR connects the calculator to the internet service where results can be graphed and communicated. 

Casio does a great job of offering a lot of capabilities for a low price.


This blog is property of Edward Shore.  2015.


  1. Excellent review, Ed! I too look forward to an inexpensive solar-powered calculator with graphing capability. Technology marches on!

  2. GCD, LCM, Int (integer part), Intg (integer part), and product (Π) - all these functions has german version of Classwiz - 991DE X

    1. the german version has 696 functions

    2. Thanks Kleo. Not sure if there are better ways to order, but I did find the German edition on ebay. Seems odd that they would strip off over 100 functions for the US market.

    3. Is there any way to change menu language to English on FX-991 DE X?

    4. Is there any way to change menu language to English on FX-991 DE X?

  3. Hello Mr. Shore!

    I did not have the chance to physically try that calculator but going through the PDF manual, it seems to have a nice feature regarding engineering units. I am not sure if I understand correctly, but looking at their example it looks like when we have a result like 1.234e3, we may press ENG to show 1234e0 or we may press SHIFT ENG to show 0.001234e6 for example. We may also do that apparently with showing engineering symbols like u, n, p, M, G, etc... I know you may say that in our head it should be easy to move the dot by three to left or right and set the exponent... But sometimes you think about a few things at the same time and don't want to lose a bit of attention so as an electronic technician having often to switch units from one to another, it's a quick nice thing.

    You, Ed, that have tried hundreds more calculators then me, have you seen something similar on others in the past?

    Keep on your good work!

  4. ...and Casio has also an Windows emulator program under this link:

  5. I have an issue with this calculator, when I set the Equation function, and try to put the coefficients for the equations it shows me the pause symbol like a ||, and I cant tip the other coefficients. Do you know why it happens?

    1. The only thing I can think of is that you will need to press the equals sign [ = ] before tip other coefficients.


  6. I would like to buy a new calculator. I'm an engineering student and I would like a calculator I could use until my licensure exams and even until I'm an engineer. Would you recommend this or the Canon F-792SGA?

    1. They both are good choices, I tend to use the Casio more between the two.

  7. This comment has been removed by the author.

  8. The fx-115es plus/fx-991es plus c also have another feature the 991EX left out....Recurring Decimals...seems very few calculators support this function.

  9. Dear Eddie,

    I am back to your blog since you are one of my favorite bloggers regarding calculators and math. Please help me figure out this problem:

    I purchased the Japan Version of this Casio Calculator (The Casio FX-JP900) This Japan Version does not contain a ratio mode but a guy on YouTube mentioned a *workaround* for ratio mode which I don't understand. Please see the image link so you can better understand what I am talking about, perhaps you can help me understand this:

    I will appreciated your prompt response.

    1. This comment has been removed by the author.

    2. The Japan version (fx-jp900) has a periodic table function as well as the LCM, GCF, etc...and can be switched to English!

  10. I have a question about this calculator, in the statistics menu when it shows us the data of a variable (Σx, Σx ^ 2, etc), what is the difference between Sx and σx ??

    1. Javier,

      Sx is the standard deviation while σx is the population deviation. The former assumes that your data set is from a sample instead of an entire population.



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