CATIGA SS-991EX Scientific Calculator with Advanced 550 Functions- Solar & Battery Powered, Multi-Function, High School & College Math, Trigonometry, Statistics, Algebra, Durable, Large Display

I was interested to see a new entry in the solar-powered scientific calculator product lineup, and one that actually brings back the possibility of functionality similar to the casio fx-991EX. There are basically three main calculators that are of roughly the same price that are solar-powered scientific calculators, with this CATIGA SS-991EX forming a strong fourth. They are now this CATIGA SS-991EX [hencefore catigaEX] casio fx-991CW, the Sharp EL-W516T, and the TI-36X Pro. The fx-991CW [henceforth casioCW] is basically a user interface change from the casio fx-991EX [henceforth casioEX]. The catigaEX is as close to a clone of the casioEX as one can get. There is a bit of a different color scheme for the buttons and case, but otherwise the layout is exactly the same. The menu system and capabilities also seem to be exactly the same as the casioEX. This is great news, in my opinion, for my tests show that the catigaEX is as fast as the casioEX, if not sometimes faster. I was not a fan of the new button layout and new menu system on the casioCW, and so the catigaEX is superior to it in my opinion, and I would actually give this as my first recommendation for a calculator in this price range and style now. All of the calculators I mentioned are going to work well for anything that does not require a graphing calculator, but the catigaEX has the fastest processor [the casioCW and casioEX have similar speed and the casioCW has a slightly better resolution screen, but hardly a dealbreaker]. A definite integral on the catigaEX is often instant and is at least 5x faster than the same calculation on the TI or Sharp calculators, about the same as the casio's. The catigaEX calculator also keeps square roots of values more consistently, allowing you to get exact answers. The catigaEX 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 catigaEX does prime factorization which allows you to get these quite easily, but it is annoying that they didn't implement them nevertheless. ] The catigaEX does clear the memory of recent calculations whenever you switch modes or the calculator turns off [the same as in the casioEX or casioCW], 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 casioEX or casioCW, the 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. A huge improvement over the casioCW is that the catigaEX uses a power of 10 button correctly. The casioCW 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. The catigaEX does the correct thing if you type 10/2E-5 by giving 5E5 (The casioCW would give 5e-5 which is why I do not recommend the casioCW given your other options.) I like the color scheme of the catiga better overall, though I miss the silver buttons from the casioEX. The build quality is very similar to the casioEX. It is a lightweight plastic calculator, but I find the button presses work well and I haven't found any problems with the ergonomics. The button layout works quite well and I find to be very easy to get used to. The TI36X pro still wins if you want memory, but it uses an old processor and is not the fastest for integration, if you care about that. Overall, any of the calculators will work, but the catigaEX is the among the fastest with the only other option still begin produced being the casioCW, which also has the best looking screen. I prefer the catigaEX over the casioCW, but either is faster than the TI36X Pro or Sharp EL-2516T. If you have a casioEX, then you may want to get a catigaEX as a backup since casio discontinued the casioEX. I'd say stick with casioEX or get a catigaEX over a casioCW, as either EX has all the same functionality (with the bonus of implementing the power of 10 button correctly). The catigaEX is my first recommendation for a solar-powered scientific calculator when you do not need graphing now.

Exelente

Easy to figure out, got me through my first year of college so far

Very good highly recommended

This is an excellent scientific calculator. It can perform many of the popular calculations that the TI-83/84 graphing calculator can perform for a fraction of the price. However, you cannot graph equations. I chose to use this calculator for my college algebra, mainly because of its cost and capabilities.

Still learning this impressive little calculator, and liking it so far. One thing I did notice though is that many of the physical constants stored in the calculator are out-of-date values. Close enough for the vast majority of needs but not up to date with the latest recommendations.

I used it for a while. Everything else is good except some keyboards are not so sensitive that I have to press them again to make it work.

Excellent and looks sharp too

It is a very useful mathematic tools. It is good to check the A-level maths calculation or the higher level maths (such as for university students). It is easy to use and durable. It is worth the money.

works great

Secondary school essential tool

It works. Not much more I can add, materials feel a little cheap, but it works, it does what it needs to do.

Good