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Reading Number lines
<ul><li>Finding the interval scales. </li></ul><ul><li>Step 1: To find out how many values each  unit  represents: (90 -80...
<ul><li>What is the value indicated with the letters? </li></ul>Recall… 80 90 1 Sub-unit 1 Unit b b)  80 + 7 =  87 a a)  8...
WB page 17 Q1 Use the number line to answer Question (I) <ul><li>Mark each of the following numbers with a cross (X) on th...
Ribbon A is 82 cm long. <ul><li>82 is between 80 and 90. </li></ul><ul><li>It is nearer to 80 than to 90. </li></ul><ul><l...
Ribbon B is 17 cm long. 10 20 15 17 17 is between 10 and 20. It is nearer to 20 than to 10. 17 is 20 when rounded off to t...
Ribbon C is 95 cm long. 90 100 95 95 95 is exactly halfway between 90 and 100. 95 is 100 when rounded off to the nearest t...
‘ Rounding off to the nearest ten’ Strategy <ul><li>A number with  1,2,3 or 4  in the ones place is rounded off to the  te...
Find all the numbers that give the following answer when rounded off to the nearest ten. <ul><li>50 </li></ul><ul><li>Answ...
Practice time... (Do Maths TB page 26 Qns 10a and b)
Find all the numbers that give the following answer when rounded off to the nearest ten. <ul><li>(ii) 570 </li></ul><ul><l...
Find all the numbers that give the following answer when rounded off to the nearest ten. <ul><li>(iii) 5000 </li></ul><ul>...
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Understand Number Lines

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Understand Number Lines

  1. 1. Reading Number lines
  2. 2. <ul><li>Finding the interval scales. </li></ul><ul><li>Step 1: To find out how many values each unit represents: (90 -80 =10) </li></ul><ul><li>Step 2: To find out how many values each sub-unit represents: (10 ÷ 10 = 1 ) </li></ul>Recall… 80 90 1 Sub-unit 1 Unit +1 +1 +1 +1 +1 +1 +1 +1 +1 +1
  3. 3. <ul><li>What is the value indicated with the letters? </li></ul>Recall… 80 90 1 Sub-unit 1 Unit b b) 80 + 7 = 87 a a) 80 + 5 = 85 +1 +1 +1 +1 +1 +1 +1
  4. 4. WB page 17 Q1 Use the number line to answer Question (I) <ul><li>Mark each of the following numbers with a cross (X) on the number line above. </li></ul><ul><li>48 35 26 </li></ul>20 30 40 50 26 35 48
  5. 5. Ribbon A is 82 cm long. <ul><li>82 is between 80 and 90. </li></ul><ul><li>It is nearer to 80 than to 90. </li></ul><ul><li>82 is 80 when rounded off to the nearest ten. </li></ul><ul><li>82 is approximately equal to 80. </li></ul><ul><li>82  80 </li></ul>80 85 90 82
  6. 6. Ribbon B is 17 cm long. 10 20 15 17 17 is between 10 and 20. It is nearer to 20 than to 10. 17 is 20 when rounded off to the nearest ten. 17 is approximately equal to 20. 17  20
  7. 7. Ribbon C is 95 cm long. 90 100 95 95 95 is exactly halfway between 90 and 100. 95 is 100 when rounded off to the nearest ten. 95  100 Why numbers with 5 in the ones place is rounded off to the next tens? The number 5 is at the centre. The convention is to round off the number to the next tens.
  8. 8. ‘ Rounding off to the nearest ten’ Strategy <ul><li>A number with 1,2,3 or 4 in the ones place is rounded off to the tens before the number. </li></ul><ul><li>A number with 5,6,7,8 or 9 in the ones place is rounded off to the next tens after the number. </li></ul>
  9. 9. Find all the numbers that give the following answer when rounded off to the nearest ten. <ul><li>50 </li></ul><ul><li>Answer: 45, 46, 47, 48, 49, </li></ul><ul><li>50, 51, 52, 53 and 54 </li></ul><ul><li>Note: The greatest value before </li></ul><ul><li>it was rounded off is 54. </li></ul><ul><li>The smallest value before </li></ul><ul><li>it was rounded off is 45. </li></ul>
  10. 10. Practice time... (Do Maths TB page 26 Qns 10a and b)
  11. 11. Find all the numbers that give the following answer when rounded off to the nearest ten. <ul><li>(ii) 570 </li></ul><ul><li>Answer: 565, 566, 567, 568, 569, </li></ul><ul><li>571, 572, 573 and 574 </li></ul><ul><li>Note: The greatest value before </li></ul><ul><li>it was rounded off is 574. </li></ul><ul><li>The smallest value before </li></ul><ul><li>it was rounded off is 565. </li></ul>
  12. 12. Find all the numbers that give the following answer when rounded off to the nearest ten. <ul><li>(iii) 5000 </li></ul><ul><li>Answer: 4995, 4996, 4997, 4998, </li></ul><ul><li>4999, 5001, 5002, 5003 and 5004 </li></ul><ul><li>Note: The greatest value before </li></ul><ul><li>it was rounded off is 5004. </li></ul><ul><li>The smallest value before </li></ul><ul><li>it was rounded off is 4995. </li></ul>

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