CCSS place value understanding to round whole numbers toand the NS 1.4G3.NBT.1 Round offUse numbers to 10,000 to the nearest ten, hundred, nearest 10 or 100. UNDERLYING SKILLS AND CONCEPTS: compare numbers; order numbers; counting thousand. Round to the Nearest Ten a K ey Ide When you round a number to the nearer ten, you decide whether it is closer to the ten before or the ten after. Numbers with 5 in the ones place are halfway between two tens. When a number is halfway between, you round up. 1 1 2 3 4 5 6 7 8 9 10 Use the hundred chart. Is 47 closer to 40 or 50? 11 12 13 14 15 16 17 18 19 20 Find 47. It is 7 squares away from 40. It is 3 squares away from 50. 47 is closer to 50. So, 47 rounds up to 50. 31 32 33 34 35 36 37 38 39 40 E x am p l E 21 22 23 24 25 26 27 28 29 30 2 Is 63 closer to 60 or 70? Find 63. It is 3 squares away from 60. It is 7 squares away from 70. 63 is closer to 60. So, 63 rounds down to 60. 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 E x am p l E 3 Is 75 closer to 70 or 80? Find 75. It is halfway between 70 and 80. So, 75 rounds up to 80. page 38 Chapter 4 – Lesson 1 C – © CSL Associates, Inc. All rights reserved. E x am p l E Name P RAC T I C E Round each number to the nearest ten. You may use the chart. 1. 21 20 2. 91 90 3. 72 70 4. 49 50 5. 87 90 6. 33 30 7. 11 10 8. 44 40 9. 56 60 10. 3 0 11. 61 60 12. 65 70 13. 15 20 14. 85 90 15. 94 90 16. 39 40 17. 5 10 18. 1 0 Solve. 25 to 34 round to 30. You can round up or round down. 19. Write six numbers that round to 30. Explain. 55 to 64 round to 60. You can round up or round down. C – © CSL Associates, Inc. All rights reserved. 20. Write six numbers that round to 60. Explain. 21. What number is halfway between 10 and 20? 22. What number is halfway between 340 and 350? Math Reasoning 15 345 Number Sense MR 1.1 23. Round 303 to the nearest 10. Explain. 303 rounds to 300. 3 is less than 5, so the ones round to 0. Keep the other digits the same. You can prove it by showing 303 on a number line. Chapter 4 – Lesson 1 page 39 MCX94.HW.CL.G3.FM&Lesson.v211 8/3/04 13:56 Page 26 Name …at home! P RAC T I C E Round each number to the nearest ten. You may use the chart. 1. 31 30 2. 1 0 3. 5 10 4. 59 60 5. 79 80 6. 35 40 7. 9 10 8. 33 30 9. 26 30 10. 2 0 11. 52 50 12. 85 90 13. 18 20 14. 75 80 15. 64 60 16. 29 30 17. 61 60 18. 31 30 Solve. 35 to 44 round to 40. You can round up or round down. 19. Write six numbers that round to 40. Explain. 65 to 74 round to 70. You can round up or round down. Explain. 21. What number is halfway between 20 and 30? 22. What number is halfway between 250 and 260? Math Reasoning 25 255 Number Sense MR 1.1 23. Round 202 to the nearest 10. Explain. 202 rounds to 200. 2 is less than 5, so the ones round to 0. Keep the other digits the same. You can prove it by showing 202 on a number line. page 26 Home Resource and Homework Chapter 4 Lesson 1 C – © CSL Associates, Inc. All rights reserved. 20. Write six numbers that round to 70. MCX94TEG3Ch01_32.v8.9.3 2/21/01 14:44 Page 73 Name P RAC T I C E Round each number to the nearest ten. You may use the chart. 1. 21 20 2. 91 90 3. 72 70 4. 49 50 5. 87 90 6. 33 30 7. 11 10 8. 44 40 9. 56 60 10. 3 0 11. 61 60 12. 65 70 13. 15 20 14. 85 90 15. 94 90 16. 39 40 17. 5 10 18. 1 0 Solve. 25 to 34 round to 30. You can round up or round down. 19. Write six numbers that round to 30. Explain. 55 to 64 round to 60. You can round up or round down. C – © CSL Associates, Inc. All rights reserved. 20. Write six numbers that round to 60. Explain. 21. What number is halfway between 10 and 20? 22. What number is halfway between 340 and 350? Math Reasoning 15 345 Number Sense MR 1.1 23. Round 303 to the nearest 10. Explain. 303 rounds down to 300. 3 is less than 5, so the ones round to 0. Keep the other digits the same. You can prove it by showing 303 on a number line. Chapter 4 – Lesson 1 Student Book Page page 39 Name …at home! P RAC T I C E Round each number to the nearest ten. You may use the chart. 1. 31 30 2. 1 0 3. 5 10 4. 59 60 5. 79 80 6. 35 40 7. 9 10 8. 33 30 9. 26 30 10. 2 0 11. 52 50 12. 85 90 13. 18 20 14. 75 80 15. 64 60 16. 29 30 17. 61 60 18. 31 30 Solve. 35 to 44 round to 40. You can round up or round down. 19. Write six numbers that round to 40. Explain. 65 to 74 round to 70. You can round up or round down. Explain. 21. What number is halfway between 20 and 30? 22. What number is halfway between 250 and 260? Math Reasoning 25 255 Number Sense MR 1.1 23. Round 202 to the nearest 10. Explain. 202 rounds to 200. 2 is less than 5, so the ones round to 0. Keep the other digits the same. You can prove it by showing 202 on a number line. page 26 Home Resource and Homework Chapter 4 Lesson 1 C – © CSL Associates, Inc. All rights reserved. 20. Write six numbers that round to 70.

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