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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 703 · 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 49 × 23? (a) 1000 (b) 10000 (c) 100
  2. 2.Best estimate of 804 + 679? (a) 1500 (b) 1300 (c) 1700
  3. 3.Best estimate of 72 × 81? (a) 560 (b) 56000 (c) 5600
  4. 4.Best estimate of 812 + 783? (a) 1800 (b) 1400 (c) 1600
  5. 5.Best estimate of 163 + 311? (a) 700 (b) 500 (c) 300
  6. 6.Best estimate of 31 × 89? (a) 27000 (b) 270 (c) 2700
  7. 7.Best estimate of 48 × 57? (a) 300 (b) 30000 (c) 3000
  8. 8.Best estimate of 79 × 14? (a) 800 (b) 8000 (c) 80
  9. 9.Best estimate of 92 × 53? (a) 4500 (b) 45000 (c) 450
  10. 10.Best estimate of 333 + 420? (a) 500 (b) 700 (c) 900
  11. 11.Best estimate of 63 × 36? (a) 24000 (b) 240 (c) 2400
  12. 12.Best estimate of 72 × 61? (a) 4200 (b) 42000 (c) 420
  13. 13.Best estimate of 139 + 384? (a) 700 (b) 300 (c) 500
  14. 14.Best estimate of 78 × 82? (a) 6400 (b) 64000 (c) 640
  15. 15.Best estimate of 13 × 29? (a) 30 (b) 300 (c) 3000
  16. 16.Best estimate of 67 × 16? (a) 140 (b) 1400 (c) 14000
  17. 17.Best estimate of 585 + 663? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 91 × 90? (a) 8100 (b) 81000 (c) 810
  19. 19.Best estimate of 226 + 836? (a) 1200 (b) 800 (c) 1000
  20. 20.Best estimate of 417 + 688? (a) 1300 (b) 900 (c) 1100
  21. 21.Best estimate of 51 × 76? (a) 4000 (b) 400 (c) 40000
  22. 22.Best estimate of 84 × 81? (a) 640 (b) 64000 (c) 6400
  23. 23.Best estimate of 446 + 695? (a) 1300 (b) 1100 (c) 900
  24. 24.Best estimate of 285 + 293? (a) 600 (b) 400 (c) 800
  25. 25.Best estimate of 98 × 77? (a) 80000 (b) 8000 (c) 800
  26. 26.Best estimate of 91 × 62? (a) 540 (b) 5400 (c) 54000
  27. 27.Best estimate of 384 + 284? (a) 900 (b) 500 (c) 700
  28. 28.Best estimate of 587 + 738? (a) 1500 (b) 1100 (c) 1300
  29. 29.Best estimate of 56 × 49? (a) 3000 (b) 30000 (c) 300
  30. 30.Best estimate of 57 × 49? (a) 3000 (b) 300 (c) 30000
  31. 31.Best estimate of 238 + 624? (a) 800 (b) 600 (c) 1000
  32. 32.Best estimate of 93 × 37? (a) 36000 (b) 3600 (c) 360
  33. 33.Best estimate of 70 × 46? (a) 350 (b) 3500 (c) 35000
  34. 34.Best estimate of 12 × 22? (a) 20 (b) 2000 (c) 200
  35. 35.Best estimate of 384 + 587? (a) 800 (b) 1000 (c) 1200
  36. 36.Best estimate of 184 + 361? (a) 400 (b) 600 (c) 800
  37. 37.Best estimate of 24 × 67? (a) 140 (b) 14000 (c) 1400
  38. 38.Best estimate of 89 × 64? (a) 5400 (b) 54000 (c) 540
  39. 39.Best estimate of 16 × 79? (a) 160 (b) 1600 (c) 16000
  40. 40.Best estimate of 34 × 36? (a) 120 (b) 12000 (c) 1200

Answer key

  1. 1000
  2. 1500
  3. 5600
  4. 1600
  5. 500
  6. 2700
  7. 3000
  8. 800
  9. 4500
  10. 700
  11. 2400
  12. 4200
  13. 500
  14. 6400
  15. 300
  16. 1400
  17. 1300
  18. 8100
  19. 1000
  20. 1100
  21. 4000
  22. 6400
  23. 1100
  24. 600
  25. 8000
  26. 5400
  27. 700
  28. 1300
  29. 3000
  30. 3000
  31. 800
  32. 3600
  33. 3500
  34. 200
  35. 1000
  36. 600
  37. 1400
  38. 5400
  39. 1600
  40. 1200

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