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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 503 · 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 33 × 43? (a) 12000 (b) 1200 (c) 120
  2. 2.Best estimate of 630 + 840? (a) 1400 (b) 1200 (c) 1600
  3. 3.Best estimate of 71 × 64? (a) 4200 (b) 420 (c) 42000
  4. 4.Best estimate of 89 × 28? (a) 27000 (b) 2700 (c) 270
  5. 5.Best estimate of 780 + 141? (a) 900 (b) 700 (c) 1100
  6. 6.Best estimate of 804 + 188? (a) 1200 (b) 1000 (c) 800
  7. 7.Best estimate of 46 × 17? (a) 100 (b) 10000 (c) 1000
  8. 8.Best estimate of 94 × 48? (a) 450 (b) 45000 (c) 4500
  9. 9.Best estimate of 507 + 221? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 878 + 652? (a) 1400 (b) 1600 (c) 1800
  11. 11.Best estimate of 74 × 61? (a) 42000 (b) 420 (c) 4200
  12. 12.Best estimate of 84 × 13? (a) 8000 (b) 800 (c) 80
  13. 13.Best estimate of 23 × 29? (a) 6000 (b) 60 (c) 600
  14. 14.Best estimate of 56 × 22? (a) 120 (b) 12000 (c) 1200
  15. 15.Best estimate of 384 + 672? (a) 1100 (b) 1300 (c) 900
  16. 16.Best estimate of 70 × 70? (a) 490 (b) 4900 (c) 49000
  17. 17.Best estimate of 525 + 630? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 523 + 562? (a) 1300 (b) 900 (c) 1100
  19. 19.Best estimate of 41 × 56? (a) 2400 (b) 240 (c) 24000
  20. 20.Best estimate of 556 + 216? (a) 1000 (b) 600 (c) 800
  21. 21.Best estimate of 86 × 23? (a) 180 (b) 18000 (c) 1800
  22. 22.Best estimate of 505 + 186? (a) 700 (b) 500 (c) 900
  23. 23.Best estimate of 757 + 340? (a) 900 (b) 1100 (c) 1300
  24. 24.Best estimate of 240 + 566? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 61 × 14? (a) 600 (b) 6000 (c) 60
  26. 26.Best estimate of 421 + 285? (a) 700 (b) 500 (c) 900
  27. 27.Best estimate of 59 × 39? (a) 240 (b) 24000 (c) 2400
  28. 28.Best estimate of 27 × 73? (a) 21000 (b) 2100 (c) 210
  29. 29.Best estimate of 867 + 807? (a) 1700 (b) 1500 (c) 1900
  30. 30.Best estimate of 54 × 27? (a) 150 (b) 15000 (c) 1500
  31. 31.Best estimate of 229 + 872? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 14 × 36? (a) 400 (b) 4000 (c) 40
  33. 33.Best estimate of 23 × 81? (a) 160 (b) 1600 (c) 16000
  34. 34.Best estimate of 91 × 56? (a) 54000 (b) 5400 (c) 540
  35. 35.Best estimate of 168 + 242? (a) 200 (b) 400 (c) 600
  36. 36.Best estimate of 36 × 59? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 556 + 868? (a) 1700 (b) 1500 (c) 1300
  38. 38.Best estimate of 88 × 19? (a) 18000 (b) 180 (c) 1800
  39. 39.Best estimate of 18 × 36? (a) 800 (b) 8000 (c) 80
  40. 40.Best estimate of 41 × 26? (a) 1200 (b) 120 (c) 12000

Answer key

  1. 1200
  2. 1400
  3. 4200
  4. 2700
  5. 900
  6. 1000
  7. 1000
  8. 4500
  9. 700
  10. 1600
  11. 4200
  12. 800
  13. 600
  14. 1200
  15. 1100
  16. 4900
  17. 1100
  18. 1100
  19. 2400
  20. 800
  21. 1800
  22. 700
  23. 1100
  24. 800
  25. 600
  26. 700
  27. 2400
  28. 2100
  29. 1700
  30. 1500
  31. 1100
  32. 400
  33. 1600
  34. 5400
  35. 400
  36. 2400
  37. 1500
  38. 1800
  39. 800
  40. 1200

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