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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 354 · 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 38 × 48? (a) 200 (b) 2000 (c) 20000
  2. 2.Best estimate of 33 × 82? (a) 2400 (b) 24000 (c) 240
  3. 3.Best estimate of 13 × 32? (a) 300 (b) 3000 (c) 30
  4. 4.Best estimate of 60 × 90? (a) 5400 (b) 54000 (c) 540
  5. 5.Best estimate of 17 × 68? (a) 14000 (b) 140 (c) 1400
  6. 6.Best estimate of 730 + 574? (a) 1300 (b) 1500 (c) 1100
  7. 7.Best estimate of 859 + 548? (a) 1600 (b) 1200 (c) 1400
  8. 8.Best estimate of 73 × 66? (a) 490 (b) 4900 (c) 49000
  9. 9.Best estimate of 579 + 144? (a) 900 (b) 500 (c) 700
  10. 10.Best estimate of 32 × 69? (a) 2100 (b) 210 (c) 21000
  11. 11.Best estimate of 94 × 68? (a) 6300 (b) 63000 (c) 630
  12. 12.Best estimate of 718 + 375? (a) 900 (b) 1100 (c) 1300
  13. 13.Best estimate of 506 + 636? (a) 900 (b) 1300 (c) 1100
  14. 14.Best estimate of 84 × 38? (a) 3200 (b) 320 (c) 32000
  15. 15.Best estimate of 624 + 303? (a) 900 (b) 1100 (c) 700
  16. 16.Best estimate of 753 + 668? (a) 1300 (b) 1500 (c) 1700
  17. 17.Best estimate of 225 + 526? (a) 900 (b) 700 (c) 500
  18. 18.Best estimate of 76 × 32? (a) 240 (b) 2400 (c) 24000
  19. 19.Best estimate of 503 + 281? (a) 800 (b) 600 (c) 1000
  20. 20.Best estimate of 87 × 92? (a) 81000 (b) 8100 (c) 810
  21. 21.Best estimate of 49 × 24? (a) 1000 (b) 10000 (c) 100
  22. 22.Best estimate of 353 + 231? (a) 800 (b) 600 (c) 400
  23. 23.Best estimate of 62 × 59? (a) 3600 (b) 360 (c) 36000
  24. 24.Best estimate of 34 × 57? (a) 18000 (b) 180 (c) 1800
  25. 25.Best estimate of 26 × 90? (a) 27000 (b) 270 (c) 2700
  26. 26.Best estimate of 92 × 96? (a) 90000 (b) 900 (c) 9000
  27. 27.Best estimate of 151 + 413? (a) 600 (b) 400 (c) 800
  28. 28.Best estimate of 68 × 17? (a) 14000 (b) 1400 (c) 140
  29. 29.Best estimate of 34 × 54? (a) 15000 (b) 1500 (c) 150
  30. 30.Best estimate of 26 × 71? (a) 2100 (b) 210 (c) 21000
  31. 31.Best estimate of 234 + 541? (a) 500 (b) 900 (c) 700
  32. 32.Best estimate of 14 × 13? (a) 100 (b) 1000 (c) 10
  33. 33.Best estimate of 94 × 71? (a) 6300 (b) 63000 (c) 630
  34. 34.Best estimate of 49 × 69? (a) 350 (b) 3500 (c) 35000
  35. 35.Best estimate of 756 + 315? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 52 × 90? (a) 450 (b) 45000 (c) 4500
  37. 37.Best estimate of 66 × 38? (a) 28000 (b) 280 (c) 2800
  38. 38.Best estimate of 36 × 47? (a) 200 (b) 2000 (c) 20000
  39. 39.Best estimate of 56 × 36? (a) 240 (b) 24000 (c) 2400
  40. 40.Best estimate of 327 + 183? (a) 700 (b) 500 (c) 300

Answer key

  1. 2000
  2. 2400
  3. 300
  4. 5400
  5. 1400
  6. 1300
  7. 1400
  8. 4900
  9. 700
  10. 2100
  11. 6300
  12. 1100
  13. 1100
  14. 3200
  15. 900
  16. 1500
  17. 700
  18. 2400
  19. 800
  20. 8100
  21. 1000
  22. 600
  23. 3600
  24. 1800
  25. 2700
  26. 9000
  27. 600
  28. 1400
  29. 1500
  30. 2100
  31. 700
  32. 100
  33. 6300
  34. 3500
  35. 1100
  36. 4500
  37. 2800
  38. 2000
  39. 2400
  40. 500

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