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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 347 · 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 875 + 229? (a) 1300 (b) 1100 (c) 900
  2. 2.Best estimate of 82 × 19? (a) 1600 (b) 160 (c) 16000
  3. 3.Best estimate of 481 + 500? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 36 × 56? (a) 2400 (b) 240 (c) 24000
  5. 5.Best estimate of 422 + 505? (a) 900 (b) 700 (c) 1100
  6. 6.Best estimate of 739 + 160? (a) 1100 (b) 900 (c) 700
  7. 7.Best estimate of 387 + 331? (a) 700 (b) 900 (c) 500
  8. 8.Best estimate of 303 + 678? (a) 1200 (b) 800 (c) 1000
  9. 9.Best estimate of 91 × 32? (a) 27000 (b) 270 (c) 2700
  10. 10.Best estimate of 605 + 877? (a) 1300 (b) 1700 (c) 1500
  11. 11.Best estimate of 869 + 817? (a) 1700 (b) 1500 (c) 1900
  12. 12.Best estimate of 22 × 66? (a) 14000 (b) 1400 (c) 140
  13. 13.Best estimate of 37 × 59? (a) 2400 (b) 24000 (c) 240
  14. 14.Best estimate of 462 + 215? (a) 500 (b) 700 (c) 900
  15. 15.Best estimate of 98 × 19? (a) 2000 (b) 20000 (c) 200
  16. 16.Best estimate of 96 × 20? (a) 200 (b) 2000 (c) 20000
  17. 17.Best estimate of 88 × 62? (a) 54000 (b) 5400 (c) 540
  18. 18.Best estimate of 722 + 261? (a) 1200 (b) 800 (c) 1000
  19. 19.Best estimate of 864 + 575? (a) 1300 (b) 1700 (c) 1500
  20. 20.Best estimate of 134 + 193? (a) 500 (b) 300 (c) 100
  21. 21.Best estimate of 79 × 23? (a) 1600 (b) 160 (c) 16000
  22. 22.Best estimate of 66 × 63? (a) 4200 (b) 42000 (c) 420
  23. 23.Best estimate of 245 + 620? (a) 600 (b) 1000 (c) 800
  24. 24.Best estimate of 222 + 559? (a) 800 (b) 600 (c) 1000
  25. 25.Best estimate of 676 + 659? (a) 1400 (b) 1200 (c) 1600
  26. 26.Best estimate of 149 + 723? (a) 1000 (b) 600 (c) 800
  27. 27.Best estimate of 17 × 92? (a) 18000 (b) 1800 (c) 180
  28. 28.Best estimate of 434 + 373? (a) 800 (b) 600 (c) 1000
  29. 29.Best estimate of 81 × 96? (a) 80000 (b) 8000 (c) 800
  30. 30.Best estimate of 36 × 58? (a) 2400 (b) 24000 (c) 240
  31. 31.Best estimate of 18 × 28? (a) 60 (b) 6000 (c) 600
  32. 32.Best estimate of 57 × 92? (a) 54000 (b) 5400 (c) 540
  33. 33.Best estimate of 430 + 734? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 325 + 178? (a) 300 (b) 500 (c) 700
  35. 35.Best estimate of 59 × 43? (a) 24000 (b) 240 (c) 2400
  36. 36.Best estimate of 610 + 361? (a) 1000 (b) 800 (c) 1200
  37. 37.Best estimate of 80 × 89? (a) 720 (b) 72000 (c) 7200
  38. 38.Best estimate of 182 + 214? (a) 200 (b) 600 (c) 400
  39. 39.Best estimate of 90 × 31? (a) 27000 (b) 270 (c) 2700
  40. 40.Best estimate of 68 × 19? (a) 14000 (b) 1400 (c) 140

Answer key

  1. 1100
  2. 1600
  3. 1000
  4. 2400
  5. 900
  6. 900
  7. 700
  8. 1000
  9. 2700
  10. 1500
  11. 1700
  12. 1400
  13. 2400
  14. 700
  15. 2000
  16. 2000
  17. 5400
  18. 1000
  19. 1500
  20. 300
  21. 1600
  22. 4200
  23. 800
  24. 800
  25. 1400
  26. 800
  27. 1800
  28. 800
  29. 8000
  30. 2400
  31. 600
  32. 5400
  33. 1100
  34. 500
  35. 2400
  36. 1000
  37. 7200
  38. 400
  39. 2700
  40. 1400

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