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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 451 · 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 86 × 24? (a) 180 (b) 1800 (c) 18000
  2. 2.Best estimate of 631 + 438? (a) 800 (b) 1000 (c) 1200
  3. 3.Best estimate of 84 × 24? (a) 16000 (b) 160 (c) 1600
  4. 4.Best estimate of 27 × 19? (a) 6000 (b) 600 (c) 60
  5. 5.Best estimate of 83 × 53? (a) 400 (b) 4000 (c) 40000
  6. 6.Best estimate of 540 + 159? (a) 900 (b) 500 (c) 700
  7. 7.Best estimate of 474 + 529? (a) 800 (b) 1000 (c) 1200
  8. 8.Best estimate of 87 × 63? (a) 5400 (b) 54000 (c) 540
  9. 9.Best estimate of 870 + 604? (a) 1700 (b) 1300 (c) 1500
  10. 10.Best estimate of 216 + 702? (a) 700 (b) 1100 (c) 900
  11. 11.Best estimate of 779 + 321? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 559 + 719? (a) 1500 (b) 1300 (c) 1100
  13. 13.Best estimate of 82 × 68? (a) 560 (b) 56000 (c) 5600
  14. 14.Best estimate of 89 × 73? (a) 6300 (b) 63000 (c) 630
  15. 15.Best estimate of 212 + 586? (a) 600 (b) 1000 (c) 800
  16. 16.Best estimate of 22 × 64? (a) 120 (b) 12000 (c) 1200
  17. 17.Best estimate of 217 + 641? (a) 600 (b) 800 (c) 1000
  18. 18.Best estimate of 19 × 68? (a) 140 (b) 1400 (c) 14000
  19. 19.Best estimate of 270 + 415? (a) 500 (b) 700 (c) 900
  20. 20.Best estimate of 288 + 327? (a) 600 (b) 800 (c) 400
  21. 21.Best estimate of 47 × 66? (a) 35000 (b) 3500 (c) 350
  22. 22.Best estimate of 16 × 56? (a) 1200 (b) 120 (c) 12000
  23. 23.Best estimate of 13 × 51? (a) 500 (b) 50 (c) 5000
  24. 24.Best estimate of 454 + 630? (a) 900 (b) 1100 (c) 1300
  25. 25.Best estimate of 163 + 583? (a) 1000 (b) 600 (c) 800
  26. 26.Best estimate of 599 + 328? (a) 700 (b) 900 (c) 1100
  27. 27.Best estimate of 570 + 617? (a) 1200 (b) 1000 (c) 1400
  28. 28.Best estimate of 37 × 21? (a) 800 (b) 80 (c) 8000
  29. 29.Best estimate of 16 × 50? (a) 1000 (b) 10000 (c) 100
  30. 30.Best estimate of 38 × 41? (a) 16000 (b) 1600 (c) 160
  31. 31.Best estimate of 873 + 166? (a) 1300 (b) 900 (c) 1100
  32. 32.Best estimate of 215 + 476? (a) 700 (b) 500 (c) 900
  33. 33.Best estimate of 93 × 64? (a) 540 (b) 5400 (c) 54000
  34. 34.Best estimate of 433 + 138? (a) 700 (b) 500 (c) 300
  35. 35.Best estimate of 862 + 791? (a) 1900 (b) 1700 (c) 1500
  36. 36.Best estimate of 89 × 93? (a) 81000 (b) 8100 (c) 810
  37. 37.Best estimate of 557 + 618? (a) 1200 (b) 1000 (c) 1400
  38. 38.Best estimate of 337 + 435? (a) 900 (b) 700 (c) 500
  39. 39.Best estimate of 40 × 67? (a) 2800 (b) 28000 (c) 280
  40. 40.Best estimate of 569 + 636? (a) 1000 (b) 1400 (c) 1200

Answer key

  1. 1800
  2. 1000
  3. 1600
  4. 600
  5. 4000
  6. 700
  7. 1000
  8. 5400
  9. 1500
  10. 900
  11. 1100
  12. 1300
  13. 5600
  14. 6300
  15. 800
  16. 1200
  17. 800
  18. 1400
  19. 700
  20. 600
  21. 3500
  22. 1200
  23. 500
  24. 1100
  25. 800
  26. 900
  27. 1200
  28. 800
  29. 1000
  30. 1600
  31. 1100
  32. 700
  33. 5400
  34. 500
  35. 1700
  36. 8100
  37. 1200
  38. 700
  39. 2800
  40. 1200

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