2 Rounding
If you are out on a shopping trip, being able to quickly estimate the total cost of your shopping could help you to decide whether you have enough money to pay for it. Approximating answers to calculations is a very useful skill to have.
Remember the rounding rhyme that will help you:
Watch this video to refresh your knowledge on rounding. You should make notes throughout:
Now try the following activities. Remember to check your answers once you have completed the questions.
Activity 15: Rounding to 10, 100 and 1 000
- Round these numbers to the nearest 10:
- a.64
- b.69
- c.65
- d.648
- e.271
- f.587
Check with our suggestions before continuing.
Answer
You can see in Figure 5 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!’)
The other answers are as follows:
- d.648 rounded to the nearest 10 is 650.
- e.271 rounded to the nearest 10 is 270.
- f.587 rounded to the nearest 10 is 590.
Now practise rounding to the nearest 100. The rule is exactly the same.
- Round these numbers to the nearest 100:
- a.325
- b.350
- c.365
- d.2 924
- e.1 630
- f.2 279
Check with our suggestions before continuing.
Answer
You can see in Figure 6 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.
The other answers are as follows:
- d.2 924 rounded to the nearest 100 is 2 900.
- e.1 630 rounded to the nearest 100 is 1 600.
- f.2 279 rounded to the nearest 100 is 2 300.
Now practise rounding to the nearest 1 000.
- Round these numbers to the nearest 1 000:
- a.4 250
- b.4 650
- c.4 500
- d.4 060
- e.31 300
- f.13 781
- g.155 600
Answer
You can see in Figure 7 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.
The other answers are as follows:
- e.31 300 rounded to the nearest 1 000 is 31 000.
- f.13 781 rounded to the nearest 1 000 is 14 000.
- g.155 600 rounded to the nearest 1 000 is 156 000.
We often round numbers in real life especially when shopping. Watch the video on the BBC Skillswise website [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] to learn more about real-life examples of rounding.
Rounding to the nearest £
The rule is that if the amount ends in 50p or more, round up to the £ above, and if the amount ends in less than 50p, the £ stays the same.
For example:
£6.32 = £6 to the nearest £ (because 32p is less than 50p)
£42.51 = £43 to the nearest £ (because 51p is more than 50p)
Activity 16: Rounding to the nearest £
Round the following amounts to the nearest £:
- £5.20
- £1.70
- £7.35
- £13.13
- £23.51
- £128.85
Answer
- £5
- £2
- £7
- £13
- £24
- £129
Activity 17: Bill’s shopping
- Bill has £20 to spend on his shopping. Here’s a list of the items he selects, along with how much they cost:
Use your rounding skills to work out whether Bill has enough money to pay for all of his shopping.
Hint: In this activity you should round to the nearest pound, so £2.20 would be rounded to £2.
Answer
Rounding all of the items should give you a total of £19 – so yes, Bill probably has enough money to pay for all of his shopping.
- Can you total all of the items on the shopping list to see what the actual cost of Bill’s shopping is?
Answer
The total cost of all of the items on the shopping list comes to £19.33, 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.