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Casio FX991 ESPLUS calculator

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£22.01 Best Offer by: rapidonline.com See more offers
3 Reviews

Brand: Casio / Type: Calculator

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    3 Reviews
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    • More +
      13.06.2013 22:42



      Must buy!

      A lot of newer Casio models are coming without solar chargers, which I am sad about as Casio are my favourite brand, and solar chargers extend the battery life massively, with no effort required at all by the user. No hassle of replacing hard to get and extremely obscure batteries from untrusted sites and sellers, just for a few extra weeks of usage out of a battered calculator. I also always had the idea that older models were inferior, until now that is. Now I see that the older models provide the same or even more functionality, for a cheaper price, and the personally, the greatest selling point for me is the solar charger.
      It has a variety of useful features, excluding the solar charger, such as Casio's "Natural View" of fractions, the ability to switch between, Radians, Degrees, and Gradians with ease, compared to other calculators of which only seem to have two of the three mathematical formats, and at that, aren't easy to convert and transfer between the two.
      I also found, by a mistake in my own working out, that it differentiates AND integrates for you, and can correct tiny mistakes instead of giving a syntax error, like auto-correct for calculators. That cuts down on the need for unnecessary brackets and multiplications etc.
      Overall, there is no reason NOT to have this calculator as it is so unbelievably good, even better than the current models. Five Star!


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    • More +
      25.02.2013 12:24



      Great quality calculator

      I have had this calculator for around 3 years and it has been thoroughly useful. It got me through my Maths IGCSE and continues to get me through my AS modules.
      I originally got this after i lost my previous calculator, which was an inferior model.
      This calculator is an old model now but it still has all the necessary functionality.
      Unfortunately there is no graphing function, by which i mean the calculator cannot show you what a graph would look like. Although this is not much of a problem it would be nice to have this feature. However it does allow you to input a function and it provides you with the points on the line or curve for specified limits.
      This calculator is very sturdy. The case it comes with which fits over the screen is extremely strong, so I am able to leave it in my bag with my heavy books and not worry that it will get damaged. The solar panel is convenient, especially if the battery chooses to die in the middle of an exam.
      So overall I would say this calculator is all I have ever needed. After reading another review i have found out that this calculator is sufficient for even university maths courses, which is quite impressive.


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    • More +
      07.01.2012 10:51
      Very helpful



      Allowed in exams so why not buy this calculator to give you the edge?

      I have only just purchased this calculator (couple of months ago) after seeing my friend using one at university. For around 4-5 years I have been a fan of the older version of this calculator, the FX 83 ES, which I have also reviewed. So far this calculator has surpassed my every expectation and I cannot give you any real reason why you shouldn't have one.

      The main reason that I like this calculator so much is because of it displaying fractions as actual fractions. This 'natural display' as Casio call it, has made inputting equations and reading off answers much simpler and reduced errors as you don't need loads of brackets to separate divisions. As for the rest of the calculator it has everything needed for someone to complete just about every exam that they will ever do!

      Also extremely useful is the fact that this calculator will integrate and differentiate for you. As long as you type in actual values the calculator can work this out and will even surmise data. This new model also boasts the ability to calculate in imaginary and complex numbers and can display the answers in either rectangular or polar form so you don't have to spend time switching between the two. Never before have I had a calculator that I don't know what every button does but actually this calculator has functions like matrices, vectors, base and a few more that I am yet to figure out and use. Therefore I am very glad that the provided instruction booklet is very helpful, I imagine anyone could use it.

      This calculator can perform trigonometry, statistics and show in radians, degrees or gradians. Personally for statistics and some other maths exams I found it easier to also have a graphical calculator by my side for help with drawing graphs and inputting statistics into tables for finding variance or similar problems. However this calculator can perform statistics for you but just not as clearly and with a little more button pressing.

      Another couple of handy features that I feel are worth a mention are the replay buttons that allow you to look through your calculation history so it saves you typing out the same calculation again and also allows for editing of calculations. The memory storage buttons are also the easiest to use that I have ever seen on a calculator. This product allows for 9 answers, numbers or calculations to be stored at once and it is simple to recall or overwrite these.

      ---Ease of Use---
      For exams or everyday use this calculator a great choice with a large clear screen and good processing power so that it hardly ever lags and you can input values quickly in a mad hurry to finish before time runs out. The buttons are fairly large so even big fingers can use them and they always fire when pressed so that you don't miss a value out accidentally and wonder why your answer is wrong. The layout of the buttons is also very efficient and after a while you realise how similar functions are grouped together nicely and you start to remember where buttons are without looking at the calculator, it's that intuitive.

      Admittedly not the main basis of what makes a calculator good but yes this sadly does affect sales. This newer model is slimmer and sleeker than before and now has a silver front with blue back and case. Again the buttons are colour coded to do with their function as pictures show clearly. The decals that are printed on the buttons are very clear and also colour coded to make use even easier. Like other models the lettering will not rub off after even years of usage.

      This calculator is very good and comes with some easy to understand instructions (though you probably know the best way to learn a calculator is to use it repeatedly, personally I became fairly familiar in just a few minutes due to its simplicity) and a sturdy lid to keep the product safe. I expect that this calculator will last me for years just like my last one did, superb build quality! A great buy for a decent and simple yet powerful calculator that is actually very cheap and does everything you need


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    • Product Details

      Short name: Casio FX991

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