fx-991CW– Advanced Scientific Calculator with High-Res 4-Tone Display | Natural Textbook Display | 540+ Functions, Numeric Calculus, Matrix Solver | Ideal for Engineering, Science & Exams

The Casio fx-991CW is an excellent calculator with very good performance and a wide range of useful features. It is easy to use, fast, and well designed, making it perfect for students and professionals who need reliable calculations. The display is clear and the overall build quality feels solid and durable. I also want to highlight that the Amazon delivery time was reasonable, especially considering that this was an international transaction. The product arrived well packaged and in perfect condition. Overall, I am very satisfied with this purchase and would definitely recommend this calculator.

Great calculator. I teach math and this is one of two non-graphing calculators I recommend. Intuitive controls and packed with a crazy amount of features that my students don't need. The build quality is fine but the buttons don't feel quite as nice as the TI competition - but I have never seen one of these fail. So it's more perception than reality. Also, I have an affinity for Casios as they were the brand of calculator wristwatch young nerdy me used to wear!

I bouught this for College Chemistry for Health Professions as a back-up to the first one (same exact one) I just bought within the past week. I LOVE this so much! It has so many functions and is so lightweight. Someone said the weight makes it feel cheap, but it is definitely NOT a cheap type of calculator. You would also think that it's "cheap", due to the low price, but this is the best scientific calculator I've ever had (and I've bought those TI ones in the past that were almost $100).

Great calculator, easy to understand, amazing functions, im uding it fot mu physics class and it is perfect for it.

There are three calculators that are of roughly the same price that are solar-powered scientific calculators. They are now the casio fx-991CW (previously the casio fx-991EX), the Sharp EL-W516T, and the TI-36X Pro. The fx-991CW [henceforth CW] is basically a user interface change from the fx-991EX [henceforth EX], with, as far as I can tell, no useful new functions and a slower (although perhaps easier to navigate) interface. The only functional additions are a dice roller and a coin flipper program, neither of much utility for the CW over the EX. [From my review of the casio EX, though the same applies to the CW for the most part: All of the calculators are going to work, but the casio [EX] has the highest resolution screen and fastest processor. A definite integral on the casio [EX] is often instant and is at least 5x faster than the same calculation on the TI or Sharp calculators. The casio [EX] calculator also keeps square roots of values more consistently, allowing you to get exact answers. The casio [EX] has all of the features that you'd expect from a scientific calculator except a GCD and LCM calculator. This is not a big deal to me, because the casio [EX] does prime factorization which allows you to get these quite easily, but it is annoying that they didn't implement them nevertheless. ] The casio CW still clears the memory of recent calculations whenever you switch modes or the calculator turns off [the same as in the ex], which I find annoying. This means that if you wanted to keep a value for the next time you turn it on, it simply isn't possible. Again, the same as the ex, the CW answer button is programmed to only keep the last value in the stack. (So if you did 2+1=3, and then put in 2+2=4, then went back to see 2+1=3, and typed +2 (Ans would be inserted for you) you would find 6, not 5.) So if you would like to use a previous result you have to scroll to it and enter it again or edit the equation from there. On a more negative note, the CW has reprogrammed the power of 10 button (commonly e or E button) such that it does not take operator precedence on the number preceding it. This means that if you type in 10/2 and get 5 then hit divide by 1E3 [E corresponding to the x10^[] button, which will show up as Ans÷1x10^3 on screen], you will get 5000 and not .005. This is contrary to the use of the power of 10 button and the ex and every other calculator handles this correctly (that is, it doesn't just treat the power of 10 button as a regular multiplication). More generally, the CW is actually noticeably slower than the EX at doing integrals. It's still fast compared to the sharp and TI counterparts, but no longer as outstanding. The CW has also done a total keyboard layout change, and relegated many functions to the catalog button. I can live with such changes, though it takes several more button presses to achieve results. The format key is somewhat annoying because you can no longer default to engineering format, but it is at least straightforward. The buttons themselves are nicely put together at least, and I actually like the more subdued look of the CW compared to the EX. Overall, any of the calculators will work, but the casio EX is the fastest with the CW having the best looking screen. I prefer the EX over the CW, but either is faster than the TI36X Pro or Sharp EL-2516T. If you have an EX, I'd say stick with it, as it has all the same functionality (with the bonus of implementing the power of 10 button correctly). A TI36X Pro is probably now the best bet if the power of 10 is make or break for you and you cannot get a reasonably priced EX. [An update from November 2025: I learned of the CATIGA SS-991EX, which now is my recommendation for a scientific calculator at this level. The CATIGA SS-991EX is essentially a clone of the casio EX, with similar (maybe slightly faster) speed and a correctly implemented power of 10 button. If you're worried about the CATIGA brand, I have found it to be equivalent to casio. If you like casio, then CATIGA products will be a seamless transition as they are identical user interfaces to the older casio calculators as far as I can tell. Since I like that user interface, I think it is actually better than the current casioCW.]

I received this calculator in perfect condition, and after using it for several months in a very demanding master’s program, I can say it works flawlessly. It’s reliable, fast, and hasn’t given me any problems at all. For anyone who needs a solid calculator for advanced studies, this one does its job extremely well.

Great quality and sleek design.

Perfect for school tests that ban fancy calculators! Our high schooler needed a simple scientific one that isn’t programmable or graphing, and this TI was on the approved list (her others weren’t). It does exactly what it needs for algebra, trig, and stats without any cheating shortcuts. Super easy to use, big clear display, nice keys. She loves it and aces her exams. Highly recommend for any student who has those strict “basic calculator only” rules!

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I got this for my son in Grade 10. It has 500+ functions in total. Clearly he's not going to need all of them. But, it 10 minutes, with the help of the 150 page PDF, it was easy enough to figure out how to do some of the basic algebra and trigonometry functions that he needs. The screen is a nice size. It shows equations, fractions, and decimals. It's clear and easy to read. You can have spreadsheets and data tables. We didn't get the calculator for all those features, but they're available. It comes with a protective case that covers the screen and buttons. The cover, when removed, clips on the back so it's easy to store.

Ótima calculadora científica, de qualidade. Esta versão sem o LA (creio que seja de Latin America), não possui idioma português, somente inglês. Comprei já sabendo disso e pra mim, tudo tranquilo.

Best calculator i ever used it does need time to learn but honestly didn’t deter me from loving it