GCSE Calculator

Which GCSE calculator should you use? The answer is simple - use the calculator your teacher recommends. Schools go to great trouble to choose calculators that are right for you and right for the syllabus you will be studying, so why buy a different type?

And there's another reason for buying the one recommended by your school and that is simply that it makes it a lot easier for your teacher if everyone is using the same model. He/she can tell you which buttons to press if you are not sure without having to visit your desk and waste precious time that could be better used teaching you something that will get you extra marks in the exam. If you are learning how to use a new function on your calculator, your teacher can take the whole class through the process together step by step.

But there's plenty more to say about calculators than that. First of all you should love your calculator and get to know it like you know the back of your hand. The last thing you want to be doing is trying to work out which keys to press in the middle of the examination. You should automatically know which keys to use for each function and you should also know which keys not to use. Remember that scientific calculators are not designed just for GCSE - they can also be used for A-Level and higher maths and so have functions that you will not use unless you study maths at this level.

You will know, of course, that there are two kinds of calculators: simple and scientific and they differ in how they treat mixed calculations. Suppose you have a sum such as 4 + 7 x 5. Technically (that is using the BODMAS rule) you should work out 7 x 5 first because multiplication is always done before addition, and then you should add the 4 at the end. A scientific GCSE calculator will do this automatically, but a simple calculator will do the 4 + 7 first and then multiply the answer by 5. So the scientific calculator will give the answer 39 (correct), but the simple calculator will give 55 (incorrect).

This is something you need to keep in mind for certain kinds of calculation such as finding the mean of a set of numbers. Suppose you need to find the mean of 23, 45, 67 and 98. With a simple calculator you must add up the numbers 23, 45, 67 and 98 and press the '=' key to get 233. Then you divide by 4 to get the correct mean of 58.25.

Now you might think a GCSE scientific calculator will take care of all this for you, but you would be wrong.

If you type 23 + 45 + 67 + 98/4 into a scientific calculator, it will think you only want the last number divided by 4 and the answer will be 159.5, which is obviously rubbish. With a scientific calculator you have two choices. You can either add up the four numbers first as with the simple calculator and then divide the answer by 4. Or you can put brackets around the addition part of the sum and divide by 4 at the end, like this: (23 + 45 + 67 + 98)/4 and this will give you the correct answer.

There are many other traps you can fall into too. Now perhaps you can see how important it is to be really familiar with your calculator before you go into the examination.

Now here's a strange thing. Have you ever thought of buying two calculators of the same type? Probably not. Well, it's a very small chance, but you could misplace your calculator just before the exam or have it stolen by some unscrupulous person who has not bothered to get their own. What are you going to do then? 

With the price of calculators at just a few pounds each these days, you could easily have two just as you would take two pens, pencils etc into the exam. I am always flabbergasted by the number of people who will spend hundreds of pounds on something like an XBox 360, but skimp on buying essential equipment for an examination or the very best revision material. Still, that's human nature I suppose.

So, make sure you know your calculator inside out and treat it as your best friend - at least until the exams are over.