Everyday maths for Construction and Engineering 1

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2 Rounding

If you are out on a shopping trip for garage parts, being able to quickly estimate the total cost of your shopping could help you to decide whether you have been given enough money to pay for it. Approximating answers to calculations is a very useful skill to have.

Figure 4 ‘Four or less, let it rest. Five or more, raise the score!’

Watch this video to refresh your knowledge on rounding. You should make notes throughout:

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Now try the following activities. Remember to check your answers once you have completed the questions.

Activity 5: Rounding to 10, 100 and 1,000

1. Round these numbers to the nearest 10:
• a.64
• b.69
• c.65

Check with our suggestions before continuing.

Figure 5 A number line

You can see that:

• a.64 rounded to the nearest 10 is 60.
• b.69 rounded to the nearest 10 is 70.
• c.65 rounded to the nearest 10 is 70. (Remember: when a number is exactly halfway, you always round up. As the rhyme goes, ‘Five or more, raise the score!’)

Now practise rounding to the nearest 100. The rule is exactly the same.

1. Round these numbers to the nearest 100:
• a.325
• b.350
• c.365

Check with our suggestions before continuing.

Figure 6 A number line

You can see that:

• a.325 rounded to the nearest 100 is 300.
• b.350 rounded to the nearest 100 is 400.
• c.365 rounded to the nearest 100 is 400.

Now practise rounding to the nearest 1,000.

1. Round these numbers to the nearest 1,000:
• a.4,250
• b.4,650
• c.4,500
• d.4,060

Figure 7 A number line

You can see that:

• a.4,250 rounded to the nearest 1,000 is 4,000.
• b.4,650 rounded to the nearest 1,000 is 5,000.
• c.4,500 rounded to the nearest 1,000 is 5,000.
• d.4,060 rounded to the nearest 1,000 is 4,000.

Hint: In this activity you should round to the nearest pound, so £4.67 would be rounded to £5.

Activity 6: Bill’s parts list

1. Bill has £30.00 to spend on his parts for a job. Here’s a list of the items he selects, along with how much they cost:
Figure 8 A parts list

Use your rounding skills to work out whether Bill has enough money to pay for all the parts.

Rounding all of the items should give you a total of £25 – so yes, Bill has enough money to pay for all the parts.

1. Can you total all of the items on the list to see what the actual cost of Bill’s shopping is?

The total cost of all of the items on the list comes to £25.05, which is very close to the answer you achieved through rounding.

Well done! You have now successfully rounded and carried out some basic number work. Can you see the importance of rounding? This is especially important when sticking to a budget.

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