Using a Scientific Calculator In Mathematics Exams

by N Pinhey

With exams approaching this is a short article with reminders and advice for anyone about to take a mathematics exam and who will need to use a scientific calculator. The most common calculator problems are:

- setting up the calculator in the right mode
- not being able to find the calculator manual !
- remembering to change calculator modes
- rounding and inaccurate answers

Why Use a Scientific Calculator?

Scientific calculators all use the same order for carrying out mathematical operations. This order is not necessarily the same as just reading a calculation from left to right. The rules for carrying out mathematical calculations specify the priority and so the order in which a calculation should be done - scientific calculators follow the same order. This order is sometimes abbreviated by terms such as BODMAS and BIDMAS to help students remember the order of doing calculations.

1st. Brackets (all calculations within bracket are done first)
2nd. Operations (eg squaring, cubing, square rooting, sin, cos, tan )
3rd. Division and Multiplication
4th. Addition and Subtraction

Being aware of this order is necessary in order to use a scientific calculator properly. This order should always be used in all mathematical calculations whether using a calculator or not.

Scientific Calculator Check

There are two types of scientific calculator, the most recent type being algebraic scientific calculators. Algebraic scientific calculators allow users to type in calculations in the order in which they have been written down. Older scientific calculators need users to press the mathematical operation key after they have entered the number.

For example to find the square root of nine (with an answer of three) press: [button]

Algebraic scientific calculator: [SQUARE ROOT] [9] [=]
Non algebraic scientific calculator: [9] [SQUARE ROOT] [=]

Both these types of scientific calculator are fine for exams, but make sure you know how to use your type.

If you are not sure whether you have a scientific calculator are not, type in:
[4] [+] [3] [x] [2] [=]

If you get an answer of 14, then you have a left to right non-scientific calculator.
If you get an answer of 10, then you have a scientific calculator as it has worked out the multiplication part first.

Lost Calculator Manuals

Calculator manuals tend to get lost very easily or you can never find them as an exam is approaching. A frequent request is what can you do if you have lost your calculator's manual? If it is a relatively new model then you can download a copy from the manufacturer's web site. If it is an old Sharp or old Casio calculator manual then you can still find these on the internet. Even with search engines, finding these manuals can take some time - the following link has information about new and old calculator manuals for Casio, Sharp, Hewlett-Packard and Texas Instruments: here.

Calculator Mode

Now that you have your calculator manual you can set your calculator to the correct settings. The standard settings are usually:

COMPUTATIONAL:
(use MODE button - choose normal not stat) NOT: SD or REG
DEGREES:
(use MODE or DRG button) NOT: RAD OR GRAD
NORMAL:
(use MODE or SETUP and arrow keys) NOT: FIX, SCI, ENG

Many calculators have a reset button on the back that can be pressed in using a pen or paper clip if you want the original factory settings.

The most common mistake is to leave your calculator in a previous mode and FORGETTING TO CHANGE IT BACK AGAIN !
(We've all done it, just try to avoid doing it in the exam !)

Common Calculator Mistakes

(a) Pressing the DRG button by mistake and not doing trigonometry questions in DEGREES mode. (If you are doing more advanced work then forgetting to change out of DEGREES mode !).
(b) Borrowing an unfamiliar calculator or getting a new calculator too close to the exam and not being familiar with the keys and how to change modes.
(c) Forgetting to write down and check work. Any exam with a calculator should have a warning on it! It is essential to write down the calculations that you're doing so that you can get method marks. You should also try and double check all calculations in case of pressing a wrong button.
(d) Rounding only at the end of a calculation. Store calculations in the memory and use all the decimal places during calculations. If you use a rounded value too soon then you will lose accuracy.
(e) Forgetting to use brackets on division calculations (e.g. when dividing by ALL the bottom part of a fraction).

Many calculators are now very powerful and have amazing computational power. Some of the programmable calculators are mini computers. Although they will all calculate 100% accurately every time, unfortunately they are only as good and as accurate as their operator!

It is often the case that candidates perform better without a calculator as it is very easy to make simple mistakes when using one. If you can do so, it certainly helps to have an idea of the rough size of the answer, so that you can see if an answer is sensible or not. It is also a good idea to repeat all key presses just in case you have made a mistake.

About the Author: Nicholas Pinhey is the designer of Revision Cards which include the best and fastest methods for the calculator and non-calculator GCSE Mathematics exam papers. Visit Revision Cards for more information on fast GCSE Mathematics revision.

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