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Estimating a Calculation – use it when you don’t want an exact answer Estimation is used when you want a rough or approximate idea for the answer to a sum

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First step is to round all the numbers in the sum Nearest ten? Nearest hundred? Nearest thousand? Nearest ten thousand? Nearest ten pence Nearest one pound or even smaller

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How to round You need to identify each place value in the number

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Place value in our system ThousandsHundredsTensOnes or units 3456 How would you read this number?

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Place value in our system ThousandsHundredsTensOnes or units 3456 Three thousand four hundred fifty six

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Place value in our system ThousandsHundredsTensOnes or units 8012 How would you read this number?

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Place value in our system ThousandsHundredsTensOnes or units 8012 eight thousand twelve There are no hundreds

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Place value in money signtensonesten pence one pence £20.12 Twenty pounds and twenty pence There is no ‘p’ here

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Place value in money ten pence one pence 43p Forty three pence There is no ‘£’ here

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How to round Now that you have identified each place value, you need to identify the halfway point

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The halfway point between forty and fifty 4050 What value is the halfway point? 45 Forty five is the halfway point?

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The halfway point between one hundred and two hundred 100200 What value is the halfway point? 150 One hundred fifty is the halfway point?

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The halfway point between eight and nine thousand 8000 9000 What value is the halfway point? 8500 Eight thousand five hundred is the halfway point?

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The halfway point between seven thousand five hundred and seven thousand six hundred 75007600 What value is the halfway point? 7550 Seven thousand five hundred fifty is the halfway point?

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The halfway point between twenty and thirty pence 20 pence30 pence What value is the halfway point? 25p Twenty five pence is the halfway point?

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What is halfway between these two sets of numbers? 30 and 40 100 and 200 700 and 800 1000 and 1100 1500 and 1600 2000 and 3000 130 and 140 0 and 1 35 150 750 1050 1550 2500 135 0.5 Did you notice that there is a five in each of these numbers?

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How to round Now that you’ve identified each place value and the halfway point - you have to decide in which half of the line your number is in

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In which half of the line ? 50 pence60 pence Round 52 pence to the nearest 10 pence. Is 52 pence closer to 50 pence or 60 pence? 55 This half Or this half?

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In which half of the line ? 30 pence40 pence Round each of these to the nearest 10p 35 This half Or this half? 34p37p31p36p35p

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In which half of the line ? £3£4 Round each of these to the nearest £1 £3.50 This half Or this half? £3.34£3.72£3.05£3.90£3.50

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In which half of the line ? £40£50 Round each of these to the nearest £10 £45 This half Or this half? £43.34£48.72£44.05£43.50£49.05

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Rounding to the nearest 10 without a number line 283 the answer is either 280 or 290 if it is a 5, 6, 7, 8 or 9 round up Round to 10 underline the tens place Look at the digit to the right to decide if it is a 0, 1, 2, 3 or 4 round down

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Rounding to the nearest 10 without a number line 8 the answer is either 0 or 0 if it is a 5, 6, 7, 8 or 9 round up Round to 10 underline the tens place Look at the digit to the right to decide if it is a 0, 1, 2, 3 or 4 round down

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Rounding to the nearest 100 without a number line 455 the answer is either 400 or 500 if it is a 5, 6, 7, 8 or 9 round up Round to 100 underline the hundreds place Look at the digit to the right to decide if it is a 0, 1, 2, 3 or 4 round down

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Rounding to the nearest 1 without a number line 1.8 the answer is either 1 or 2 if it is a 5, 6, 7, 8 or 9 round up Round to 1 underline the ones place Look at the digit to the right to decide if it is a 0, 1, 2, 3 or 4 round down

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Rounding to the nearest 10p without a number line £0.08 the answer is either 0p or 10p if it is a 5, 6, 7, 8 or 9 round up Round to 10p underline the 10p place Look at the digit to the right to decide if it is a 0, 1, 2, 3 or 4 round down

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Rounding to the nearest £1 without a number line £2.05 the answer is either £2 or £3 if it is a 5, 6, 7, 8 or 9 round up Round to £1 underline the £1 place Look at the digit to the right to decide if it is a 0, 1, 2, 3 or 4 round down

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When rounding to the nearest ten – these are possible answers 0010203040 5060708090 100110120130140 150160170180190 200210220….

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When rounding to the nearest 100 – these are possible answers 0100200300400 500600700800900 10001100120013001400 15001600170018001900 200021002200….

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When rounding to the nearest 10 pence – these are possible answers 0p10p20p30p40p 50p60p70p80p90p £1.00£1.10£1.20£1.30£1.40 £1.50£1.60£1.70£1.80£1.90 £2.00£2.10£2.20….

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When rounding to the nearest £1 – these are possible answers £0£1£2£3£4 £5£6£7£8£9 £10£11£12£13£14 £15£16£17£18£19 £20£21£22….

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When rounding to the nearest £10 – these are possible answers £0£10£20£30£40 £50£60£70£80£90 £100£110£120£130£140 £150£160£170£180£190 £200£210£220….

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