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What is the best calculator for maths at school?

13th July, 2024

Why is it important to have the best calculator?


Nowadays we are never far from a calculator – available on any smart phone or computer, some of them more powerful than a regular handheld one. You can get many ‘standalone’ calculators, often for a specific use (e.g. accounting).

But one that is designed for (and approved by most) schools is the CASIO fx-83GTX (battery-operated) or CASIO fx-85GTX (solar-powered) calculator.

This calculator has many useful features, all that help for taking GCSE maths.

I recommend this calculator too for adults, such as those taking Functional Skills maths, numeracy reasoning tests, or wanting to improve their general maths confidence.

Rather than wait until shortly before an exam, it is important to get used to the features of this (or any alternative calculator) as soon as you can – which is why I suggest getting this calculator from the start of year 7.


Why not use a phone calculator?


I have students who ask, “Why can’t I use my phone calculator?”. The simple answer is, “You can, but…”

– Phones, and other electronic devices that access the internet, are not allowed in exams

– Phone calculator apps cannot usually represent/show fractions, and can therefore cause inaccuracies in subsequent calculations due to rounding errors.

– Fewer features


CASIO Calculator – I prefer the solar-powered version (fx-85GTX) as you don’t need batteries, but the battery-operated (fx-83GTX) one is slightly cheaper.

A couple of useful features of the CASIO fx-83GTX / fx-85GTX


How to convert from fraction to DECIMAL with a calculator

Let’s say, for example, you perform a calculation and want to express the answer as a decimal.

“What is 6 divided by 10? Show your answer as a decimal.”

You enter 6 divide by 10, press equals button, and it shows you 3/5 (i.e. as a fraction). That’s not a decimal!

Answer – use the “SD button” – it’s the one above the DEL button that has S<>D (it means converts surds to decimals).

Press it once and it changes the 3/5 into 0.6

CASIO fx-85GT x - SD button

“But,” I hear you say, “Doesn’t the phone app calculator already give me the answer as a decimal?” Yes, that is the default format it gives, but it won’t change it into a fraction.

Press the SD button again, on the CASIO calculator, and it will change 0.6 back to 3/5

How to convert from improper fraction to MIXED NUMBER with a calculator

Let’s say, for example, you want to convert an improper fraction (aka top-heavy fraction) to a mixed number (a whole number and fraction)

“What is 6/5 as a mixed number?”

You enter 6 divide by 5, press equals button, and it shows you 6/5 (i.e. what you entered).

Answer – use the “SD button” again, but use the ‘SHIFT’ button first – it’s the top-leftmost button, just below the screen.

Press shift (let go) and then press the SD button. The shift button extends the functionality of each button on the CASIO calculator, with the feature shown in gold above that button being activated.

CASIO fx-85GT x - shift button

More features of CASIO FX-83GTX / FX-85GTX

If you want to know about all the features of these calculators, a manual is available from Casio – Casio FX-83GTX and FX-85GTX User Guide

Nicola Bhalerao - Warwick Tutor

About Me

My name is Nicola Bhalerao and I am a private tutor based in Warwick. Since 2013, I have provided one-to-one tuition for children and adults. I specialise in maths tutoring, but cater for different requests, ranging from 11+ / entrance exams to various uses of maths, e.g. : interviews, job promotions, GCSE retakes, Functional Skills, nursing, teaching – any situation where confidence in maths is required.

My background is in computing, with a Computer Science degree from Warwick University. I have worked many years as a programmer, latterly in the games industry. Both my sons were tutored by me for the 11+ (they went to a local grammar school). I received training for teaching secondary school maths and I am fully CRB checked.

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