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Succeed with maths: part 1

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# 6 Calculator exploration: negative numbers

Using a calculator for negative numbers can make life a lot easier!

You have plenty of options when it comes to what calculator to use and you may find it easier to use the one that you are most familiar with. This could be a calculator on your mobile phone, computer or tablet, an online calculator, or a handheld calculator.

To enter a negative number on a calculator you will usually use the (plus/minus) key or the (-) key.

Find either of these keys now.

How you enter a negative number will depend upon the calculator you are using. For most newer calculators you will need to press the or the (-) key and then enter the number.

You may be wondering which key to use on your keyboard for negative numbers. There is no direct equivalent of the button, but the minus key performs the same task.

Table 1 Minus operator buttons
Mathematical operation Calculator button Keyboard key
Negative number or (-) The − (minus) key

Now you can have a go at some examples using a calculator.

## Activity 6 Adding and subtracting negative numbers using the calculator

Timing: Allow approximately 10 minutes

Work out the answers to the following questions in your head first to get some more practice. Then check that they are correct on the calculator.

• a.2 + (–5)

### Answer

• a.Remember the rule that adding a negative number is the same as subtracting the corresponding positive number.

2 + (–5) = 2 − 5 = –3

• b.(–4) − 3

### Answer

• b.(–4) − 3 = –7
• c.8 − (–5)

### Answer

Remember the rule that subtracting a negative number is the same as adding the corresponding positive number.

• c.8 − (–5) = 8 + 5 = 13
• d.(–10) + (–2)

### Answer

• d.(–10) + (–2) = (–10) − 2 = –12
• e.(–3) + 3

### Answer

• e.(–3) + 3 = 0