CATIGA Black Scientific Calculator with Textbook-Style HD Display, Solar & Battery Scientific Calculators for College, High School & Engineering Students, Icon Menu & Magnetic Hard Case, CS-991NX

Purchased for grandchildren to use at school. Functionality good for them. Purchased reasonably .

This reasonably-priced calculator is perfect for use in Algebra I class!

Does what it needs to do for the price, feels extremely cheap. If you’re ballin on a budget def choose this one.

Grandson broke his other calculator. Needed replacement but didn't need to be graphing. This one fit the bill. Does same steps.

I am very impressed with the easy way this calculator works. I bought several through Amazon because I needed one in specific for a special needs child so I could as her great grandmother assist with her math. She is not able to use this due to her needs but I can now help her. Impressed

I have to say that I am impressed with this calculator, especially for the price. The last serious calculator I bought was a TI-85 more than a few years ago. I remember those being quite an investment, but it still works and I still use it, so I guess I can't complain too much. I was pleasantly surprised to see how much functionality you can now get in a relatively inexpensive scientific calculator. To think at one point teachers used to tell kids- you might not always have access to a calculator!! The CATIGA CS-991NX is lightweight, easy to carry in your bag or purse, and uses solar power with battery backup- which is a plus so you don't have to remember to have back-up batteries. It has a good range of functions for high school and college-level math and science courses, including matrix calculations, and the icon-based menu makes it fairly easy to find what you need without memorizing a million key combinations. The textbook-style display is also helpful because equations appear in a format that looks more like what you would actually see in a math book, although I will admit that the screen is a little smaller than my old TI-85 that I’m used to, but it is still perfectly usable. I also like that it comes with a magnetic hard case and is available in several colors, which is a nice touch for students. One increasingly important advantage of a dedicated calculator is that there are still plenty of exams where a calculator may be permitted but phones, computers, and AI tools are definitely not. For that situation, this gives you a lot of capability in a small, inexpensive package. My only real complaint is the instruction booklet. It is surprisingly complete—which is practically a miracle these days—but the print is microscopic. Get out your reading glasses if you plan on helping the kids or using it yourself if you are over 35! Overall, this seems like a very good value for students taking algebra, trigonometry, statistics, chemistry, physics, engineering, or other courses that need more than a basic calculator. Lots of useful functions, a friendly menu, lightweight design, and a price that won’t make you feel like you just purchased laboratory equipment. Happy to recommend!

I acquired the CATIGA CS-991NX for schoolwork and have been pleased with how it performs. It responds quickly when I enter calculations, and the textbook-style display makes expressions easier to read than a single line of numbers and symbols. That is particularly useful when I want to check what I entered before moving on to the next problem. The calculator has a good range of functions for student use. I like the icon menu because it makes the different modes easier to find instead of requiring me to remember a long sequence of key presses. The magnetic hard case is a useful addition, too. It gives the calculator some protection when I put it away, and the unit itself feels durable. The overall quality is good for the money. Battery life has also been good in my use. The solar and battery power setup is reassuring for something I may need throughout a school day. I have not had to think much about power while using it, which is exactly how I want a calculator to work. Between the speed, display, and available functions, it feels like a practical tool rather than a calculator I will outgrow immediately. I think this is a good value for a high school or college student who needs a scientific calculator. There may be a little time spent learning where the less familiar functions are, as there would be with any calculator that does this much. I would also check a class or exam’s calculator rules before relying on it for a test. For regular coursework, though, I have found it fast, capable, and easy to read. The sturdy feel and good battery life make me comfortable keeping it in my school bag.

The included manual is quite thick. And the whole manual is written in English. No other pages are devoted to other languages. So the manual is quite comprehensive. The calculator is well made, with no case separation during twisting effort. It is very solid. The cover is held on by magnets. They are not as strong as I would have liked. The cover is secure, but either a snap-on or stronger magnets would've been preferred. The keys feel comfortable, and the contrast on the characters makes it easy to read. The characters on the far left side, like the pi symbol, are printed on the case's curve. This feature doesn't affect readability, but it's a poor design choice. The keys themselves can skip registering button presses when pressed rapidly. For example, alternating button presses of 1 and 2 results in something like 1212122221222122122221. If done slowly, it shows the pattern 12121212... correctly. Fundamental calculator precision tests were passed. However, the solver function for a basic equation took longer to complete than expected. The LCD screen is a bit difficult to read under soft lights. It can only be viewed if looking directly at the screen. It's almost as if there is privacy filter installed, which I don't believe is the case.

I, literally, cannot begin to understand all of the functions and capabilities of this device. I am of an age where I lived through the introduction of the first 4 function calculators and whether universities would allow them or prohibit them from being used during exams. I remember, as an engineering student, using a slide rule and also that I could count on making at least one slide rule error on every exam. That made it worthwhile for me to spend hundreds of dollars on a Hp 35 - the first scientific calculator. This calculator puts my Hp 35 to shame! The 140 page (all English) user manual is necessary and more like a textbook. I've bought less complicated cars! To be honest, some of the subjects that require the capabilities of this device are probably at least at senior level university courses, if not graduate levels. But, just because you may not understand how to use all of its capabilities does not diminish its utility to you! A terrific device at a miniscule price. At the operational level, I like the magnetic cover that guards the keyboard against keys from accidental (and unintended) pressing. On the other hand, a device this complex is really incomplete if it doesn't have an available output device (i.e. printer or storage) to retain its how it has been used and the results it has generated for proofing/validation and verification.

This pink scientific calculator (model CS-991NX) is a solid pick for homeschool families who want to be prepared before advanced math lessons arrive. The textbook-style HD display shows fractions, roots, exponents, and equations the way they actually appear in a textbook, using 4-gradation shading rather than squeezing everything onto one flat line. The icon menu makes it simple to switch between Calculate, Statistics, Distribution, Spreadsheet, Table, and Equation modes with a single tap, which keeps input fast and makes mistakes easier to catch. With 538 functions built in, this calculator covers everything from General Math and Pre-Algebra through Algebra, Geometry, Trigonometry, Statistics, and Calculus, along with Physics, Chemistry, and Engineering applications. It handles matrices, vectors, complex numbers, equation and inequality solving, and even has a built-in spreadsheet, plus 47 scientific constants and 40 unit conversions. I picked this one up for my daughter, and while she is not quite into algebra and trig yet, it is nice having it on hand so it is ready to go once her lessons reach that point. It means less scrambling to find the right tool later and gives her a chance to get familiar with the layout ahead of time. The dual solar and battery power setup means there is no risk of it dying mid-lesson down the road, and the included magnetic hard case feels much sturdier than the flimsy slide-on covers a lot of other calculators come with. At just 6.38 x 3.03 x 0.42 inches and 0.21 pounds, it is compact and easy to toss in a bag or pencil case. For any homeschool family looking to plan ahead for upcoming math courses, this calculator offers plenty of tools in a slim, durable package that will grow right alongside your student.

This blue scientific calculator (model CS-991NX) is a great pick for students moving into more advanced math courses. The textbook-style HD display shows fractions, roots, exponents, and equations the way they actually appear in a textbook, using 4-gradation shading rather than squeezing everything onto a single line. The icon menu makes it easy to switch between Calculate, Statistics, Distribution, Spreadsheet, Table, and Equation modes with one tap, which helps speed up input and catch mistakes before they become a problem. With 538 functions on board, this calculator is built to cover a wide range of courses, from General Math and Pre-Algebra all the way through Algebra, Geometry, Trigonometry, Statistics, and Calculus, plus Physics, Chemistry, and Engineering applications. It handles matrices, vectors, complex numbers, equation and inequality solving, and even includes a built-in spreadsheet, along with 47 scientific constants and 40 unit conversions. I picked this one up for my son as we homeschool, and I wanted something that could grow with him as his math courses get more advanced, so having this many functions in one device means we likely won't need to buy a second calculator as he progresses. The dual solar and battery power setup is a nice touch, since it means there is no risk of the calculator dying mid-lesson or mid-test, and the included magnetic hard case feels much more secure than the flimsy slide-on covers that come with a lot of other calculators. At just 6.38 x 3.03 x 0.42 inches and 0.21 pounds, it is compact enough to toss in a backpack or pencil case without adding bulk. For any student heading into higher level math, whether in a traditional classroom or homeschool setting, this calculator offers a lot of tools in a slim, durable package. Just remember to double check the approved equipment list if you plan to use it for exams.

Every scientific calculator in this price range claims a full function list. The CS-991NX claims 538, covering matrices, vectors, complex numbers, base-n, distributions, a spreadsheet mode and 40 unit conversions. That is the same broad territory as the usual class-standard models, so it comes down to how the thing is built and how fast you can move through it. The natural textbook display is the real feature. Fractions, roots and exponents render the way they are written instead of collapsing onto one line, which means you can proofread your own input before hitting equals. The icon menu handles mode switching in a tap rather than making you memorize a numbered list. Solar with battery backup is the right power arrangement for a device that sits unused in a bag for weeks at a time. And the case genuinely stands out. A rigid magnetic snap-on cover instead of the slide-on sleeve that goes missing by October is a small design decision with a long payoff. One thing to sort out before you buy: check your exam board's approved-equipment list. Feature-rich calculators with spreadsheet and solver modes are not universally permitted, and that is on the board, not the hardware. At 43 CAD, the build and display justify it.

This scientific calculator is essentially a knock-off of the Casio fx-991CW with some minor layout differences. Similar to the original, it has an abundance of features and functions that can easily get you through high school and university math. It is easy to read fractions, exponents, and multi-step equations on its large display. The buttons are responsive, and it functions very similarly. The icon menu made navigating and switching between the different modes easier. For basic scientific calculator functionality purposes, it would be hard to tell the difference. However, the build quality feels lower than the original. The plastic used in this calculator and its protective case feels cheap and is very lightweight. On the other hand, some people might actually prefer the lighter weight. Also, the protective cover is magnetic and securely snaps into place for transport. Unfortunately, I've never needed to learn or use the more complicated features of this calculator, so I can't comment on how well this version replicates more demanding calculations, but I can confirm that this calculator is at least sufficient for what I used the original for, which was high school and business degree math. Something else to note is that this calculator claims to be dual power and run on solar power with battery backup when light isn't available. However, if you take out the battery, this calculator doesn't seem able to run on solar power alone, which makes me think this is just battery-powered.