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Estimating an answer remember to round first before you do the sum.

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Presentation on theme: "Estimating an answer remember to round first before you do the sum."— Presentation transcript:

1 Estimating an answer remember to round first before you do the sum

2 At the sweet shop look at the prices Mars 33pPolo 23p Twix 28pGum 45p Estimate the price of a Mars and a Polo Remember to round the prices first

3 At the sweet shop : first round the prices Mars 33pPolo 23p Twix 28pGum 45p Estimate the price of a Mars and a Polo 30p + 20p = 50p Why round to 10p?

4 Estimating an answer remember to round first before you do the sum  What will you round to? Look at the number and decide what makes sense?  Whatever you choose stick to it!

5 At the sports shop look at the prices shorts £12.50tee shirt £8.35 socks £5.60 hat £4.50 Estimate the price of a hat and socks

6 At the sports shop: first round the prices shorts £12.50tee shirt £8.35 socks £5.60 hat £4.50 Estimate the price of a hat and socks £5 + £6 = £11 Why round to £1?

7 At the sports shop: look at the prices shorts £12.50tee shirt £8.35 socks £5.60 hat £4.50 Estimate the price of shorts and a tee shirt

8 At the sports shop: first round the prices shorts £12.50tee shirt £8.35 socks £5.60 hat £4.50 Estimate the price of shorts and a tee shirt £10 + £10 = £20 Why round to £10?

9 At the computer shop look at the prices printer £112.50memory £58.35 keyboard £35.60monitor £154.50 Estimate the price of two keyboards and extra memory

10 At the computer shop: first round the prices printer £112.50memory £58.35 keyboard £35.60 monitor £154.50 Estimate the price of a two keyboards and extra memory £40 + £40 + 60 = £140 Why round to £10?

11 At the computer shop look at the prices printer £112.50memory £58.35 keyboard £35.60 monitor £154.50 Estimate the price of a printer and a monitor

12 At the computer shop: first round the prices printer £112.50memory £58.35 keyboard £35.60 monitor £154.50 Estimate the price of a printer and a monitor £100 + £200 = £300 Why round to £100?

13 Estimating an answer  remember to round first before you do the sum  round all to the same degree of accuracy  then do the sum


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