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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 210 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 84 × 69? (a) 5600 (b) 56000 (c) 560
  2. 2.Best estimate of 284 + 777? (a) 900 (b) 1100 (c) 1300
  3. 3.Best estimate of 86 × 76? (a) 72000 (b) 720 (c) 7200
  4. 4.Best estimate of 23 × 98? (a) 200 (b) 20000 (c) 2000
  5. 5.Best estimate of 18 × 62? (a) 12000 (b) 1200 (c) 120
  6. 6.Best estimate of 83 × 23? (a) 1600 (b) 16000 (c) 160
  7. 7.Best estimate of 766 + 270? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 17 × 91? (a) 18000 (b) 1800 (c) 180
  9. 9.Best estimate of 66 × 13? (a) 70 (b) 7000 (c) 700
  10. 10.Best estimate of 312 + 878? (a) 1200 (b) 1000 (c) 1400
  11. 11.Best estimate of 76 × 66? (a) 5600 (b) 56000 (c) 560
  12. 12.Best estimate of 81 × 86? (a) 7200 (b) 72000 (c) 720
  13. 13.Best estimate of 18 × 56? (a) 12000 (b) 120 (c) 1200
  14. 14.Best estimate of 614 + 535? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 52 × 16? (a) 10000 (b) 100 (c) 1000
  16. 16.Best estimate of 786 + 622? (a) 1600 (b) 1400 (c) 1200
  17. 17.Best estimate of 752 + 215? (a) 1000 (b) 1200 (c) 800
  18. 18.Best estimate of 689 + 368? (a) 1300 (b) 900 (c) 1100
  19. 19.Best estimate of 60 × 54? (a) 300 (b) 30000 (c) 3000
  20. 20.Best estimate of 37 × 84? (a) 320 (b) 32000 (c) 3200
  21. 21.Best estimate of 68 × 96? (a) 70000 (b) 700 (c) 7000
  22. 22.Best estimate of 57 × 47? (a) 3000 (b) 30000 (c) 300
  23. 23.Best estimate of 120 + 198? (a) 100 (b) 300 (c) 500
  24. 24.Best estimate of 36 × 14? (a) 4000 (b) 40 (c) 400
  25. 25.Best estimate of 52 × 19? (a) 100 (b) 10000 (c) 1000
  26. 26.Best estimate of 33 × 18? (a) 600 (b) 6000 (c) 60
  27. 27.Best estimate of 694 + 523? (a) 1000 (b) 1200 (c) 1400
  28. 28.Best estimate of 57 × 26? (a) 1800 (b) 18000 (c) 180
  29. 29.Best estimate of 749 + 134? (a) 600 (b) 800 (c) 1000
  30. 30.Best estimate of 81 × 44? (a) 32000 (b) 3200 (c) 320
  31. 31.Best estimate of 878 + 239? (a) 900 (b) 1100 (c) 1300
  32. 32.Best estimate of 360 + 266? (a) 700 (b) 900 (c) 500
  33. 33.Best estimate of 170 + 707? (a) 900 (b) 700 (c) 1100
  34. 34.Best estimate of 93 × 38? (a) 360 (b) 3600 (c) 36000
  35. 35.Best estimate of 735 + 870? (a) 1800 (b) 1400 (c) 1600
  36. 36.Best estimate of 52 × 81? (a) 4000 (b) 400 (c) 40000
  37. 37.Best estimate of 22 × 39? (a) 8000 (b) 800 (c) 80
  38. 38.Best estimate of 593 + 411? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 71 × 63? (a) 420 (b) 42000 (c) 4200
  40. 40.Best estimate of 424 + 560? (a) 1200 (b) 800 (c) 1000

Answer key

  1. 5600
  2. 1100
  3. 7200
  4. 2000
  5. 1200
  6. 1600
  7. 1100
  8. 1800
  9. 700
  10. 1200
  11. 5600
  12. 7200
  13. 1200
  14. 1100
  15. 1000
  16. 1400
  17. 1000
  18. 1100
  19. 3000
  20. 3200
  21. 7000
  22. 3000
  23. 300
  24. 400
  25. 1000
  26. 600
  27. 1200
  28. 1800
  29. 800
  30. 3200
  31. 1100
  32. 700
  33. 900
  34. 3600
  35. 1600
  36. 4000
  37. 800
  38. 1000
  39. 4200
  40. 1000

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