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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 657 · 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 26 × 78? (a) 24000 (b) 240 (c) 2400
  2. 2.Best estimate of 77 × 88? (a) 72000 (b) 7200 (c) 720
  3. 3.Best estimate of 66 × 74? (a) 490 (b) 4900 (c) 49000
  4. 4.Best estimate of 215 + 813? (a) 1000 (b) 1200 (c) 800
  5. 5.Best estimate of 79 × 74? (a) 560 (b) 5600 (c) 56000
  6. 6.Best estimate of 48 × 76? (a) 40000 (b) 400 (c) 4000
  7. 7.Best estimate of 80 × 73? (a) 56000 (b) 5600 (c) 560
  8. 8.Best estimate of 525 + 582? (a) 1300 (b) 900 (c) 1100
  9. 9.Best estimate of 28 × 58? (a) 18000 (b) 1800 (c) 180
  10. 10.Best estimate of 46 × 84? (a) 4000 (b) 40000 (c) 400
  11. 11.Best estimate of 428 + 145? (a) 300 (b) 500 (c) 700
  12. 12.Best estimate of 453 + 540? (a) 800 (b) 1200 (c) 1000
  13. 13.Best estimate of 529 + 710? (a) 1000 (b) 1200 (c) 1400
  14. 14.Best estimate of 44 × 44? (a) 160 (b) 16000 (c) 1600
  15. 15.Best estimate of 22 × 29? (a) 6000 (b) 60 (c) 600
  16. 16.Best estimate of 36 × 29? (a) 12000 (b) 120 (c) 1200
  17. 17.Best estimate of 304 + 836? (a) 900 (b) 1100 (c) 1300
  18. 18.Best estimate of 778 + 295? (a) 900 (b) 1100 (c) 1300
  19. 19.Best estimate of 92 × 16? (a) 1800 (b) 180 (c) 18000
  20. 20.Best estimate of 60 × 72? (a) 420 (b) 4200 (c) 42000
  21. 21.Best estimate of 267 + 169? (a) 300 (b) 500 (c) 700
  22. 22.Best estimate of 272 + 595? (a) 700 (b) 1100 (c) 900
  23. 23.Best estimate of 734 + 195? (a) 1100 (b) 700 (c) 900
  24. 24.Best estimate of 80 × 82? (a) 6400 (b) 640 (c) 64000
  25. 25.Best estimate of 670 + 729? (a) 1200 (b) 1600 (c) 1400
  26. 26.Best estimate of 21 × 18? (a) 400 (b) 40 (c) 4000
  27. 27.Best estimate of 68 × 92? (a) 6300 (b) 630 (c) 63000
  28. 28.Best estimate of 76 × 86? (a) 7200 (b) 72000 (c) 720
  29. 29.Best estimate of 80 × 48? (a) 400 (b) 4000 (c) 40000
  30. 30.Best estimate of 487 + 259? (a) 600 (b) 1000 (c) 800
  31. 31.Best estimate of 83 × 78? (a) 640 (b) 6400 (c) 64000
  32. 32.Best estimate of 61 × 74? (a) 420 (b) 42000 (c) 4200
  33. 33.Best estimate of 66 × 46? (a) 35000 (b) 3500 (c) 350
  34. 34.Best estimate of 43 × 62? (a) 2400 (b) 240 (c) 24000
  35. 35.Best estimate of 121 + 529? (a) 600 (b) 400 (c) 800
  36. 36.Best estimate of 794 + 766? (a) 1600 (b) 1800 (c) 1400
  37. 37.Best estimate of 38 × 66? (a) 2800 (b) 28000 (c) 280
  38. 38.Best estimate of 654 + 397? (a) 900 (b) 1100 (c) 1300
  39. 39.Best estimate of 57 × 77? (a) 480 (b) 4800 (c) 48000
  40. 40.Best estimate of 329 + 663? (a) 1000 (b) 1200 (c) 800

Answer key

  1. 2400
  2. 7200
  3. 4900
  4. 1000
  5. 5600
  6. 4000
  7. 5600
  8. 1100
  9. 1800
  10. 4000
  11. 500
  12. 1000
  13. 1200
  14. 1600
  15. 600
  16. 1200
  17. 1100
  18. 1100
  19. 1800
  20. 4200
  21. 500
  22. 900
  23. 900
  24. 6400
  25. 1400
  26. 400
  27. 6300
  28. 7200
  29. 4000
  30. 800
  31. 6400
  32. 4200
  33. 3500
  34. 2400
  35. 600
  36. 1600
  37. 2800
  38. 1100
  39. 4800
  40. 1000

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