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Rounding Numbers. 6 7 8 6.3 7.2 7.8 67 890 = 68 000 2035 = 2040 8985 = 9000 6.89 = 6.9.

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Presentation on theme: "Rounding Numbers. 6 7 8 6.3 7.2 7.8 67 890 = 68 000 2035 = 2040 8985 = 9000 6.89 = 6.9."— Presentation transcript:

1 Rounding Numbers. 6 7 8 6.3 7.2 7.8 = 2035 = 2040 8985 = 9000 6.89 = 6.9

2 Rounded Numbers All Around You.
Here are some examples of rounded numbers which could appear in newspaper headlines: Watch Scotland Win Again. March In War Protest. Man Leaves £2 Million To Charity. ©Microsoft Word clipart

3 Rounding To The Nearest Whole Number.
6.7 Consider the number : It is our task to decide if the number is closer to : 6 7 Look at the number line below: or 6 7 8 6.5 6.7 Mark the number 6.5 6.5 is the midpoint between 6 and 7. Mark the number 6.7 Is 6.7 closer to 6 or 7 ? Is 6.7 above or below 6.5 ? Above 6.7 = 7 (to the nearest whole number)

4 Further Example. Round the following to the nearest whole number:
(1) 24.3 24 25 26 24.3 24.5 What is the midpoint between 24 and 25 ? Is 24.3 above or below 24.5 ? Below. 24.3 = 24 (To the nearest whole number).

5 What Goes In The Box ? Round the following to the nearest whole number: NB: always round 0.5 up . Ie = 13 (to the nearest whole number). (1) 4.8 5 (6) 287.6 288 (2) 7.4 7 (7) 9.8 10 (3) 44.6 44 (8) 49.6 50 (4) 87.5 88 (9) 99.7 100 (5) 56.3 56 (10) 399.5 400

6 Rounding To 1 Decimal Place.
Round 4.67 to one decimal place (1d.p). 4.6 4.7 4.67 4.65 What number is the arrow pointing at ? Mark 4.67 on the number line . Is 4.67 closer to 4.6 or 4.7 ? 4.7 4.67 = 4.7 (to 1d.p)

7 Round to 1 d.p . 19.5 19.6 19.53 19.55 What number is the arrow pointing at ? Mark on the number line . Is closer to 19.5 or 19.6 ? 19.5 19.53 = 19.5 (to 1d.p)

8 What Goes In The Box ? 2 Round the following to 1 decimal place.
(1) = 34.7 (5) = 60 (6) = 40 (2) = 17.7 100 (3) = 24.8 (7) = (8) = 1000 (4) = 41.9

9 Rounding To 2 Decimal Places.
In order to make this a faster process we will take a different approach: Round to 2 decimal places ( 2 d.p). 7 What number is the second after the point ? Is the number after the seven greater or smaller than 5 ? 8 is greater than 5 (or 8 > 5) Rule If the number is greater than or equal to 5 then round up. Now round to 2 d.p = (to 2 d.p)

10 Round 23.482 to 2 decimal places ( 2 d.p).
What number is the second after the point ? Is the number after the eight greater or smaller than 5 ? 2 is less than 5 (or 2 < 5) Rule If the number is greater than or equal to 5 then round up. Now round to 2 d.p = (to 2 d.p)

11 What Goes In The Box ? 3 Round the numbers below to 2 decimal places.
(1) = 45.78 (5) = 37 (2) = 37.68 (6) = 99.99 0.1 (3) = 6.46 (7) = 0.43 (4) = (8) = 1000

12 Rounding To The Nearest 10,100,1000 etc.
Round 467 to the nearest ten. 6 Which number is the tens number ? 7 > 5 Is the number after the 6 greater or smaller than 5 ? Rule If the number is greater than or equal to 5 then round up. Now round 467 to the nearest ten. 467= 470 (to the nearest ten). 460 470 467

13 Round 23 438 to the nearest hundred.
Which number is the hundreds number ? 3 < 5 Is the number after the 4 greater or smaller than 5 ? Now round to the nearest hundred. Rule If the number is greater than or equal to 5 then round up. 23 438= (to the nearest hundred). 23 400 23 500 23 438

14 What Goes In The Box ? 4 Round the numbers below to the required unit:
(1) to the nearest ten = 34 570 (2) to the nearest hundred = 47 900 (3) to the nearest thousand = (4) to the nearest ten thousand =


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