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Using a Calculator


Here is an image of the Casio Classwiz Calculator, it is a popular calculator for GCSE maths.

classwiz

You should have a calculator similar to this. If your calculator is slightly different it should still have all the same buttons, they may just be in different places.

Above the buttons you can see more functions in yellow. These are accessed by pressing SHIFT and then the button. The cube root button is pressed by pressing SHIFT then the square root button (one after the other, not at the same time).

Calculator buttons cube root = Calculator buttons shiftCalculator buttons square root

Squaring Numbers

We can square numbers on our calculator using the square button. Find the button on your calculator that looks like this:

Calculator buttons square

If you type a number into your calculator followed by the square button and the equals button the calculator will return answer.

Example: Use your calculator to work out the value of 5.62²

We type into the calculator

Calculator buttons 5Calculator buttons decimal pointCalculator buttons 6Calculator buttons 2Calculator buttons squareCalculator buttons equals

You calculator should give an answer of 31.5844


Cubing Numbers

We can cube numbers in the same way using the cube button:

Calculator buttons cube

Example: Use your calculator to work out the value of 7.8³

We type into the calculator

Calculator buttons 7Calculator buttons decimal pointCalculator buttons 8Calculator buttons cubeCalculator buttons equals

You calculator should give an answer of 474.552


Other Powers

We can raise a number to any power using the power button:

Calculator buttons power

Example: Use your calculator to work out the value of 2.9⁴

We type into the calculator

Calculator buttons 2Calculator buttons decimal pointCalculator buttons 9Calculator buttons powerCalculator buttons 4Calculator buttons equals

You calculator should give an answer of 70.7281


Try these:


Square Rooting

We can square root numbers on our calculator using the square root button. Find the button on your calculator that looks like this:

Calculator buttons square root

Press the square root button first, then type in the number that you want to square root, then press equals.

Example: Use your calculator to work out the value of √562

We type into the calculator

Calculator buttons square rootCalculator buttons 5Calculator buttons 6Calculator buttons 2Calculator buttons equals

You calculator may give an answer of √562
To convert this to a decimal we need to use the SD button:

Calculator buttons SD

If we press this button we should get an answer of 23.70653918


Cube Rooting

To cube root numbers we need to find the cube root button. On the calculator above it is accessed by pressing SHIFT then square root.

Calculator buttons cube root

Press SHIFT, then square root, then type in the number that you want to cube root, then press equals.

Example: Use your calculator to work out the value of ∛68

We type into the calculator:

Calculator buttons shiftCalculator buttons square rootCalculator buttons 6Calculator buttons 8Calculator buttons equals

We should get an answer of 4.081655102


Other Roots

There is also a way to find other roots. On the calculator above it is SHIFT then the power button.

Calculator buttons root = Calculator buttons shiftCalculator buttons power

Press SHIFT, then the power button, then type in the root you want, then press the right button (from the direction pad at the top, in the middle, of the calculator), then the number you want to root.

Example: Use your calculator to work out the value of ∜100

We type into the calculator:

Calculator buttons shiftCalculator buttons powerCalculator buttons 4Calculator buttons rightCalculator buttons 1Calculator buttons 0Calculator buttons 0Calculator buttons equals

We should get an answer of 3.16227766


Try these:


The Fraction Button

The calculator has a fraction button which can be used to write fractions. The button looks like this:

Calculator buttons fraction

If you press the fraction button you should see a fraction in the input area. We can move between the numerator and denominator of the fraction by pressing the direction buttons.

Example: Convert  3⁄8  to a decimal.

We need to write  3⁄8  into the calculator.

We type into the calculator:

Calculator buttons fractionCalculator buttons 3Calculator buttons downCalculator buttons 8Calculator buttons equals

This will give an answer of  3⁄8  to convert to a decimal we need to press the SD button.

Calculator buttons SD

This will give an answer of 0.375


Example: Work out the value of:  3.25 + 1.2⁄0.7² 
Give your answer as a decimal.

We can type this into the calculator exactly how it looks in the question:

We type into the calculator:

Calculator buttons fractionCalculator buttons 3Calculator buttons decimal pointCalculator buttons 2Calculator buttons 5Calculator buttons plusCalculator buttons 1Calculator buttons decimal pointCalculator buttons 2Calculator buttons downCalculator buttons 0Calculator buttons decimal pointCalculator buttons 7Calculator buttons squareCalculator buttons equals

This will give an answer as a fraction, so we press the SD button to convert to a decimal

Calculator buttons SD

This will give an answer of 9.081632653


Mixed Numbers

We can also write mixed numbers into the calculator by pressing SHIFT then the fraction button.

Calculator buttons mixed number = Calculator buttons shiftCalculator buttons fraction

Example: Convert  3 2⁄5  to an improper fraction.

To type the improper fraction into the calculator we press:

Calculator buttons shiftCalculator buttons fractionCalculator buttons 3Calculator buttons rightCalculator buttons 2Calculator buttons downCalculator buttons 5Calculator buttons equals

This gives an answer of   17⁄5

If we want to convert an improper fraction back to a mixed number we can press SHIFT then SD. This will convert between improper fractions and mixed numbers.


Try these:

The Time Button

We can use this button to calculate with time:

Calculator buttons time

We can use the time button to convert a decimal answer into hours and minutes

Example: Convert 7.2 hours into hours and minutes

We can type 7.2 into the calculator:

Calculator buttons 7Calculator buttons decimal pointCalculator buttons 2Calculator buttons equals

Then press the time button

Calculator buttons time

We can read the answer as 7 hours and 12 minutes.

Example: Convert 3 hours and 48 minutes into hours

To type a time into the calculator we write the number of hours, then the time button, then the number of minutes, then the time button (then the number of seconds and the time button)

To type in 3 hours and 48 minutes we press:

Calculator buttons 3Calculator buttons timeCalculator buttons 4Calculator buttons 8Calculator buttons timeCalculator buttons equals

We can then press the SD button (twice)

Calculator buttons SD

This gives an answer of 3.8 hours.

We can also use the time button to add up times.

Example: A film starts at 8:30pm and runs for 105 minutes, work out the time when the film ends.

We can type this into the calculator:

Calculator buttons 8Calculator buttons timeCalculator buttons 3Calculator buttons 0Calculator buttons timeCalculator buttons plusCalculator buttons 0Calculator buttons timeCalculator buttons 1Calculator buttons 0Calculator buttons 5Calculator buttons timeCalculator buttons equals

The answer can be read as 10:15 pm


Try these:


The ANS button

The ANS button stores your last answer

Calculator buttons ans

We can use this button when we want to use our answer for another calculation.

If we type 3 × 5 into the calculator and then press equals:

Calculator buttons 3Calculator buttons timesCalculator buttons 5Calculator buttons equals

The answer (15) is now stored as ANS

We can then do calculations using the ANS button

Calculator buttons ansCalculator buttons plusCalculator buttons 3Calculator buttons equals

We should get an answer of 18


Storing Numbers in the Memory

We can also store numbers in the calculator using the STO button.

Calculator buttons STO

When we have an answer we can press STO and then one of the keys with a pink letter above. We have the letters A, B, C, D, E, F, X, Y and M.

We can type 2 × 5 into the calculator and press equals to get an answer of 10

Calculator buttons 2Calculator buttons timesCalculator buttons 5Calculator buttons equals

We want to store the answer so we press STO and the letter we want to store it as. We will store the answer as A so we press:

Calculator buttons STOCalculator buttons negative

Our answer will now be stored as A.

We can use A in calculations by pressing ALPHA then A:

Calculator buttons ALPHACalculator buttons negative

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A calculator is only as good as the input you type. In GCSE questions, you need to enter the expression exactly as written, then decide whether to copy the display or round.

If a question says "write down all the figures on your calculator display", do not round or drop zeros. If your calculator shows a fraction but the question wants display figures, use the decimal-change key such as S-D or S⇔D.

For example, 4.7+2.35=7.054.7+2.35=7.054.7+2.35=7.05, so you must write 7.057.057.05 exactly. The zero matters because it shows the hundredths digit.

Questions

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Question 1

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Find 1.69\sqrt{1.69}1.69​

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What does an exam instruction to "write down all the figures on your calculator display" mean?

Using a Calculator Revision Guide

  1. GCSE
  2. /Maths
  3. /Using a Calculator

Revision notes for Edexcel GCSE Maths Using a Calculator. Open the guide for explanations and worked examples. Written against the Edexcel GCSE Maths (1MA1) specification, so the content matches what's examinable rather than general Maths background.

Revision guides

Practise questions

1 of 2

Use your calculator to work out 4.234.2^34.23.

Practise questions

1 of 3

Calculate the value of 18.6+5.43.2−1.7\frac{18.6 + 5.4}{3.2 - 1.7}3.2−1.718.6+5.4​. Give your answer to 1 decimal place.

Practise questions

1 of 2

Use your calculator to work out the fourth root of 818181, written as 814\sqrt[4]{81}481​.

Practise questions

1 of 3

Calculate the exact value of 16.81+2.520.53\frac{\sqrt{16.81} + 2.5^2}{0.5^3}0.5316.81​+2.52​.

Practise questions

1 of 2

Convert 716\frac{7}{16}167​ to a decimal.

Practise questions

1 of 3

Calculate 3.52+16.813.5^2 + \sqrt{16.81}3.52+16.81​.

Practise questions

1 of 2

Convert 5.755.755.75 hours into hours and minutes.

Practise questions

1 of 3

Calculate 3.5+2.1×4.83.5 + 2.1 \times 4.83.5+2.1×4.8. Give your answer as a decimal.

Practise questions

1 of 2

A calculator gives 4×7=284\times7=284×7=28. What is the value of ANS−9\text{ANS}-9ANS−9?

Practise questions

1 of 2

You calculate 2×52\times52×5 and store the answer as AAA. What is the value of A+7A+7A+7?