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For Casio FX-991 ES PLUS, 903 customer reviews collected from 1 e-commerce sites, and the average score is 4.7.

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9.9.2010

I bought the older version of this calculator 5 months before my GCSE maths exams. Even at this level I felt at a massive advantage: you can type in equations like 3y+1=5 and it will solve them. It also has a special mode which solves quadratic, cubic and simultaneous equations. Another time saver is when you want to repeat the same operation multiple times rather that scrolling along them replacing the number, for example if you wanted a list of what the value of a number cubed minus its value squared rather than entering 2^3 - 2^2 then 3^3 - 3^2, 4^3 - 4^2 ect. You could just:1. Enter X^3 - X^22. Press CALC3. Enter the value you want X to be and press =4.Repeat steps 2 and 3 for whatever values you wantWith a medium sized function which you need to input say ten values you could more than quarter the time.I have just finished AS level maths and the new functions that are useful are non-symbolic integration and differentiation this means you cannot derive X^2 to 2X (calculators which do this are banned in UK exams) but you derive the function X^2 when X is 3, to equal 6. It also solves logs to the base of any real number as well as calculating the sums of sequences using the sigma notation.The applied module it took was statistics and for this you can just enter the data you have been given and it is able to calculate the values for linear regression lines the PMCC, Sxx Syy Sxy, min max, mean, range etc. It can do other types of regression but I have no use for these yet, in fact I have not use for most of the features of this calculator and it's still incredibly useful, it can do so much means it's probably the calculator of choice from GCSE to PhD. Even though I have a graphic calculator I use this 99% of the time for shear ease of use.Even when preparing for the non-calculator exams like some GCSE papers and core 1 (C1) at A-level this is useful as you can check your answers quickly or if needed do your homework very quickly on the bus to school.I would like to say this calculator is no substitute for hard work and proper understanding of the concepts. While it is true you only will really be able to use this calculator with ease and unlock its potential if you could do a question without the calculator if required and I would only recommend using it as a time saver, especially if you want to do a maths related degree.That said it can still get you marks where you shouldn't deserve them. At GCSE level they gave marks if the correct answer was seen even if no working was shown. So for one 5 mark question I did just that and I think got it right. Then at A-level I was stuck on one part which upon using the cubic equation solver showed me the correct method. These small marks could be the difference between whether a university accepts or rejects you, which for only [...] is a bargain.Just to finish a note of the differences between normal and the PLUS version. I terms of build quality there is very little difference. The new one is slightly more stylish. Functionally the PLUS version will show the answer to quadratic, cubic and simultaneous equations in surd form which the older model doesn't, this can earn you marks on some exams that require a surd for answer for the next question.This calculator is top of its range but lower models have features which this one doesn't: The two main cheaper models amazon currently sell (as of 08/2011) are the
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2.5.2014

I recall my parents owning a basic Sharp LED calculator in the early '80s, running from a 9v battery; small, heavy and two-toned cream/terracota brown! Going through night school and university 20 years ago with a wonderful Casio fx100-d Super FX (still have it, still going strong! Casio build quality!), that old fx100-d was well used - I studied mathematics for 7 years (two degrees) and can assure readers that even that basic tool (compared to today's display machines) was well-designed, thought-out and offered maths users a genuine tool for calculations and learning.Fast forward to recent days, and I was reminded of the usefulness and importance (to me as fan of maths and electrical engineering)of having a good calculator on hand 'at all times'. Rather than 'risk' my cherished fx-100d to be carried out and about nowadays, I decided to get a cheap, modern descendant.You end up working best with machines and marques that you've used in the past: some are ardent HP fans (and I admit the economy and logic of RPN calculations!), Sharp, Texas Instruments (got a TI-85, but never gelled with it)... They all have their own quirks, menu methods, keyboard layouts, terminology... I'm a Casio man, so after some enjoyable internet searching, bought a Casio fx-991ES Plus from a high street store. The low price and 'FX' branding made me feel nostalgic at the genealogy of my early university friend.Initial impressions: packed with features, advanced (to me!) display with surd or decimal expressions and evaluations, solvers, matrices, ... it's a busy little machine. I suppose symptomatic of modern calculators, where technology allows so much computing power and calculations across statistics, calculus, matrices, engineering, complex numbers, ...to manage the amount of choices, the design resorts to menus and sub-menus rather than the extra real estate of more buttons.Some niggles: lightweight, hard plastic shell and not 'flat', as others have noted - not a tactile delight when sitting on a table and as you press buttons, it rattles away like a bad computer keyboard.The 'Natural Visually Perfect Algebraic Method' takes some getting used to: the advantage is you enter calcs as you would right them, e.g. [SIN] [(] [3][0] [)] [=] . The downside is more key strokes to get the answer (older Casios offered [3][0][SIN] to get the answer).I'm also disappointed that the ENGineering mode as lost the useful keyboard-based buttons with units for milli, micro, nano, pico, femto, kilo, mega, giga.... you need to apply the correct powers of 10 to calculate in these units. Bugs me, but likely a non-event for others.Overall, as a cheap, content-rich, large display scientific calculator, I like it as an everyday machine. It will likely last for decades as Casios are that well-built. On the flipside, the low price point ensures a replacement is never an expensive alternative.Recommended.
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27.5.2014

Although I think this calculator is not perfect, I gave five stars because nothing comes close as far as I know among calculators you can use in exams.The good: The natural display make it much easier to use than other calculators and has a range of very useful functions. Some of which like (CALC) and sum function will save time in the exam, some others like numerical integration, differentiation lets you double check your calculations so that you can be absolutely certain that they are correct, and notice any errors. There's a useful guide how to make the most out of it: [...]The bad: The main issue is the limited hardware. It's annoying to find I can't type in an iterative expression because there's a character limit of 99 characters.Similar frustration occurs when memory is dumped when changing modes, or can't see the history for as many calculations as I want. Or when I can't just use vector calculations as I want fractions and vectors only work with decimals. It's also annoying that in vector mode using variables is more complicated and you only get 3. I found it a bit disappointing that there's no product function, even though the manual says so. Once you use one of the non-standard modes it starts to get a bit complicated and time-consuming to deal with the menus. You can only use the natural display in the standard mode. (you have to use conventional linear display in the others). A good example of complicated menus is the vector mode (part of A-level maths):Every vector operation requires you to press 3 buttons: (shift) + (5) (gives the list of options to choose from) and a number next to the option you need. For example for the dot product you can't just press the decimal dot button, you have to go through the same menu. You can choose the vector variables the same unintuitive way. When choosing the dimensions of the vector you need to press (1) for 3 dimension, and (2) for 2. Again this is unintuitive. Because of this simple vector-calculations are faster if you do them in the normal mode.Note to manufacturer: In the next version of this calculator I would like to see fewer more intuitive menus, for example rather than pressing 3 buttons for the dot in vector mode it would be better to just use the decimal dot button instead. Rather than pressing 2 buttons to get the [vector], [matrix] etc menus there should be a special button which brings up the appropriate menu in each mode. The menu options should be easier to remember: eg to press 3 for a 3 dimensional vector, press the button with A over it (-) to get VctA in the vector menu. Also I would like better hardware. probably it would cost a fraction of a penny to be able store like 200 characters instead of 100.
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28.4.2012

Casio has always been my favourite calculator company (I haven't had the pleasure to play with a Texas Instruments). I purchased this calculator almost a year ago for my first A-Level calculator exam (Core 2)to replace my fx-83es that I used at GCSE, and have never looked back.It has all the functions of the fx-83es (natural display, scientific functions, radians etc) and so much more. the main differences between the fx-83es and the fx-991esplus are as follows:Integration and differentiation is a main selling point for me. Calculus functions are only numerical, so are only useful for checking you have the right answer (you still have to put in the hard work to learn how to integrate and differentiate).calculus functions do not work on parametric equations, though.The CALC function allows you to enter any equation (eg f(x)=4x³ - 6x² + 7x -4) and substitute values of x. Essential for trial & improvement, remainder theory, etc.The equation function allows you to enter simultaneous (with either 2 or 3 unknowns), linear, quadratic, and cubic equations to find all your values of X, Y and Z (Y and Z on simultaneous equations only).The SOLVE function is only useful on linear equations, as it only provides 1 value of x. Although, its trial and improvement algorithm will allow you to use trig functions.The calculator is pre-programmed with 40 scientific constant, with a legend on the inside of the case. As a physics and chemistry student, this has saved me from having to flick through the formula book during exams, saving valuable minutes. Having constants pre-programmed into the calculator also means I can't make a mistake in using the wrong constant, or copying it down incorrectly.The calculator does have a complex number mode, although as a normal maths (not further maths) student, I have never needed to learn how to use it.However, the reason I gave the fx-991esplus 4 stars and not 5 is that the build quality does leave some to be desired. Although it has withstood the abuse that comes from being by a student's side for a year, the plastic feels a bit flimsy, and at first glance, it looks like something from the 1970s - otherwise it would be a perfect non-graphic scientific calculator.The bottom line - This is an essential calculator for any student studying maths or science (or both) at A-Level. It won't do your maths paper for you, but it will allow you to make sure you have the right answer, so you can go back and trace your mistakes. Make sure, however, that you pop the calculator case back on before you throw it into your back at the end of lessons - otherwise, the build quality might let you down.
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27.4.2014

To start off with, the delivery of the calculator was swift even with free postage, having received it within 3 days of ordering.The first thing you notice about the calculator is the fact it is very light, and made of what feels like relatively cheap plastic, but this isn't the problem. The main problem with the build quality is the fact it does not lay evenly on the table without its cover. The solution to this though would be to file down one of the corners with some sand paper, so it's hardly anything to cry over.I bought this calculator to replace my old SHARP EL-531W which started to run out of battery. I decided to opt for a whole new calculator instead of buying more batteries as I realized that for university,the SHARP would not be sharp enough. *Insert laughter here*The Casio provides many, many more functions in comparison to the SHARP which is expected given the price difference. The display is great! I can finally view an entire equation without having to scroll along the display. If you're doing A-level maths, then this is a no-brainer. I managed to get through my GCSE's with the SHARP, so maybe a cheaper calculator would suffice for those still in secondary school, but it's still worth looking at if you're planning on doing any maths intensive subject at A-Level.Another great thing that comes with the calculator is a help manual for people less experienced with Casio calculators like myself.One important thing to note is that when doing division, the answer will usually come up as a fraction, but you can change this to a decimal if you wish. Instructions are in the manual.As I said before, the only issue is the build quality and the fact it does not lie flat on a table without the cover, but apart from that it certainly goes above and beyond what I require it for.
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9.2.2012

Although I would like to give this calculator five stars I feel that I'm going to have to keep the manual by my side so have to dock a few stars. I don't think the modes and setup are very user friendly. I know if I don't use some of the features frequently on this calculator I'm going to forget where to find it in all the menus there are. Shame because it is really a good calculator. If I have to re-learn how to set up the thing each time I want to change from complex to stat etc then I'm just going to pick up an older calculator and use that instead. I still not sure between comp mode and complex mode. I've read the manual twice now,carrying out all the examples throughout the whole manual and still not confident.I know what the other reviewers mean about the cheap feel. My opinion is that whilst I don't find it feels cheap, it certainly looks cheap because all the buttons move around in there holes so don't stay straight, each row of buttons are all out of alignment with each other. Very strange, what were Casio thinking? The thing looks like its been under a bus.Other wise would have been the best out there. If I don't find my way round the menus ok over the next few months I'll ebay it and get a sharp or texas. Can any body suggest a replacement? Are Texas or Sharp calculators easier to use?Will update my review in a month or twoActually found some good video examples for this calc on y ou t ube, feel a bit happier with the functionality now.The buttons are still wonky though. Will still need my manual by its side.I've decided to up my rating from three stars to four. This is becasue I have been looking at calculators in the shops and this one wins hands down there. I've also been getting practice from Y outube with has helped immensely. The keys are still wonky though!
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10.4.2011

Whilst the calculator has a negative side the overall feel of this calculator is that it is perfectly satisfactory. I shall start with the negative. I have owned a couple of casio calculators in the past and they have all been extremely well built and sturdy to use. This calculator is the first I have used which genuinely feels cheap, the buttons are tacky and make annoying sounds and rotate easily within their pits. However, I haven't had any trouble with breakages or buttons not registering my presses, it just seems shoddily built.On the plus side the calculator is easily adequate for most levels of mathematicians. I currently study AS maths and have found lots and lots of functions that I have never heard of,let alone need. The main reason for me buying this was the ability to integrate and differentiate to check my answers, as well as solve quadratic equations. On top of this the calculator can work with imaginary numbers, solve up to cubic equations, use matrices and lots of other niceties.For such a cheap price relative to the top end calculators I don't see the need to lash out on something which will break the bank, I can see this lasting at least up to early maths degree level if one chooses to take this route and for now I'm glad I decided to upgrade. Don't think twice about buying this (unless you feel the need to drop it from above a couple of metres, after which it is sure to break).Summary:Cons - cheap build qualityPros - lots of features which will be adequate for a large chunk of maths progression
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30.4.2012

Prior to this calculator, I used a Casio FX 991 ES (an old model). After losing it, I decided to upgrade to the ES-Plus. I was pleased to have upgraded -- the ES-Plus is a fully featured calculator yet the features are not too intrusive to hinder every day, 'casual' operations (such as simple addition).When wanting to do something a little more complex (e.g. complex numbers, vector products, matrices etc.), a simple shift into a different mode and the calculator becomes even more powerful. A particular feature which is useful for the GCSE mathematician is the equation solving function (which can be used to check an answer after working it out by hand) -- this can be used to solve linear,quadratic and cubic equations. For AS and A2 mathematicians, the statistic functions (such as regression) are useful -- regression calculations can take a lot of working, so it's satisfying to be able to check that you're right using a calculator function! Complex/Imaginary modes and vector modes are particularly helpful in Further Pure modules. Another feature which I found useful is the 'table' function -- this allows you to calculate a series of values for a certain function in a certain range. I have used this many times in Further Pure 2 when having to draw polar graphs!Arguably, the build quality isn't superb, but you have to remember that this is one of the cheapest calculators you can buy: and for how powerful it is, it is certainly worth it.
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25.6.2011

I bought this calculator just before my final A-Level maths exams took place after it was highly recommended to me by a friend. I used it both in C2 and in C4 (the only two I was doing this time) and I have to say that it is absolutely amazing. I really wish I had this calculator from GCSE onwards. It is able to easily solve quadratic, cubic and simultaneous equations, you just type them in (look how to do this on YouTube, it's quite simple) and it will generate the answer for you. I have never been quick at solving quadratics or cubics so during C2 and C4 the ability to solve them using this calculator was priceless.The other thing I really liked about this calculator is that it does integration with limits,for C4 you will need to integrate at least one an equation with limits (integration is a big topic on C4) and show your working out, which can sometimes be a 6 or 7 mark question, this calculator won't show you the working but it will give you the exact answer so that when you are done with the question you can use the calculator to check if you are right or not, which could possibly save you quite a few marks (it really helped me).To sum it up this calculator is well worth the money, even if you are just thinking of buying right before your exams as it most likely will gain you marks. Also this calculator is NOT on the banned calculator list by Edexcel (not sure about other exam boards though).
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3.1.2012

Arrived this morning, and I've been tinkering around with the many features for a couple of hours during the day - yep, that's how many there are! The layout is just like all Casio calculators (especially the most recent 83/85 GT calculators), just with more features, so it's really easy to get used to.There are so many things you can do, I'm still in disbelief - definite calculus, equation solving, vectors, matrices, and everything you could possibly want for statistics.. you name it, it can do it.What I also like is the ability to use constants such as atm pressure, Planck's constant, Earth's gravitation field strength and so on, at the touch of a button,along with being able to convert between what seems like every unit man has ever known.People comment about the build quality being quite poor, and I can see what they mean - however I have had the 85GT (exactly the same build) for over three years now, and it still looks and works as new, so there's no real complaints to be had - the new form factor is also lighter, slimmer, and easier on the fingers :) (also less effort when pressing those keys allows for rapid-fire button combos!).If you are considering a Casio, there is no question to be asked - it has to be the 991ES PLUS, and if you are in the UK sitting A-level Maths, this is the best calculator in the world for you. I have absolutely no regrets.
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23.5.2012

How can the words that I type in any way do justice to the powers of this beautiful creature that the lord has provided us? In my darkest hour this calculator lifted me from the shadows. It renewed my faith in all that is human and opened my eyes to the divine being that is maths. This is more than a calculator. This, to me, is a true friend. It has uplifted me rejuvenating my joie de vivre helping me to overcome my social inadequacy.Allow me to present to you just one of the millions of examples where this calculator has rescued me. One bleak Friday morning, I awoke and made my way to school. An average day you might say. But then I chanced upon some rogue youths.Any other day this would have struck fear into my heart. But upon this day, nothing could stop me, for I (the chosen one) had at my side the FX 991ES (or sir Lancelot as he is known by his closest friends). I struck out at the juvenile delinquents bearing my calculator for all to see. He struck with a fist of iron, deadly and unforgiving. The beast was stunned. I successfully integrated my way back into society.I urge you to embark on your own voyage of discovery, into the world of mythical, magical creatures. Embrace your maths side. Conquer those vectors. Vanquish those evil integral functions.BUY HIM X
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21.9.2016

Works perfectly fine, and does what it says on the box. Calculates. There are so many things you can do with this and luckily my teachers have only really made us use half of them. It's really useful to be able to store a few values and use letters in place of them. If you get this calculator, i'm assuming you need it for an A level or something, read up on all the things you can do with it. There are so many features and just by looking them up you can learn a fair amount of maths.My crazy maths teacher Robin has some weird fetish for calculaters and owns an abundance of them, all different models and types, (He told us he has a glass cabinet for them, we're not too sure if he's lying or is actually insane.You probably have to be to teach Maths at A level) and this according to him is a sound model. Working out integrals can be daunting and fairly slow using the in built function but it's better than actually doing it yourself.Sorry to Casio for the 3 stars but if i wasn't taking maths i probably would give it 4/5. Seriously maths is painful and this calculator is a dreadful reminder of all the work we have to do for it. Saying that though, i probably wouldn't be able to get through maths without it, and it is a handy tool.
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1.5.2017

This calculator is a must have for GCSE. It gives you a strong advantage over students that would not have this calculator as it can solve mostalgebraic equations such as linear, quadratic and even cubic equations. It also has scientific constants (as shown in the photo) making it incredibly useful in physics exams and it also has the ability to convert units which is extremely useful. There is a steep learning curve between this and a traditional calculator but if you ever get stuck there a plenty of tutorials on youtube about how to use this calculator.Before buying I would check whether this is allowed with your exam board,I think all exam boards allow it but I cannot guarantee you your exam board will allow it.Bottom Line:It is definitely worth paying a premium for this calculator. It gives you a significant advantage in the exams. It does not fully answer the question as it does not give you the workings out but it is far easy (in my experience at least) to put the workings to the answer rather than figuring it out from scratch.If you have any questions don't hesitate to comment below, I will try to answer them. If you found this review helpful in anyway please press the "yes" or "helpful" button
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19.5.2013

This particular model of the standard Casio scientific calculator is probably the best. Among it's many added features are scientific and mathematical constants, unit conversions, vector functions, advanced statistical functions, differentiation, intergration, finding the sum of an arithmetic progression, solving algerbraic equations and solving quadraic and cubic and simultaneous equations.There are some functions that other, cheaper models have that this doesn't. For example, the Casio FX-83GTPLUS has recurring decimals. However, overall this is the best calculator for all the additional functions you do get on this.The alternative to this would be a graphic calculator, but for A-level and GCSE maths,this is perfect. A graphic calculator comes with the small side disadvantage of costing an arm and a leg, weighing as much as a newborn and not having natural display. Furthermore this calculator has natural display, making it easier to key in calculations and graphics calculator doesn't. It is also easier to carry and for the number of functions it has, it is very cheap.In conclusion, this is the most practical, easy to use scientific calculator out there.
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23.6.2012

By far, this is the best calculator in the world. It is so immense in its usefulness, I can hardly describe it in words.I used this calculator for all my A Levels. Maths, Further Maths, Chemistry, this was INVALUABLE. The reason for this? It's natural display. Rather than fiddling with 100 brackets and symbols, on this calculator you can enter complex sums and fractions naturally, as the display shows the fraction on 2 lines, like it would be in your textbook or exam paper. This makes it so much easier to input sums, and understand what is going on.Also, it has inbuilt functions for integrating and differentiating. You can't use X in this, only an actual number. But if you assume say X=2,and work out the integral of the question from your exam as X=2 on the calculator, you get answer.If this is the same answer as you get from putting X=2 into your simplified equation in your exam, YOU KNOW IT MUST BE CORRECT - and you have those marks! So it's great as a checker in exams.It's just brilliant. If you are doing A levels you need this device! I'm still using it at University.
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