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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 624 · 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 56 × 82? (a) 48000 (b) 480 (c) 4800
  2. 2.Best estimate of 609 + 761? (a) 1600 (b) 1400 (c) 1200
  3. 3.Best estimate of 46 × 77? (a) 40000 (b) 4000 (c) 400
  4. 4.Best estimate of 16 × 98? (a) 2000 (b) 200 (c) 20000
  5. 5.Best estimate of 87 × 50? (a) 45000 (b) 450 (c) 4500
  6. 6.Best estimate of 66 × 62? (a) 4200 (b) 420 (c) 42000
  7. 7.Best estimate of 703 + 463? (a) 1000 (b) 1200 (c) 1400
  8. 8.Best estimate of 29 × 12? (a) 300 (b) 3000 (c) 30
  9. 9.Best estimate of 493 + 729? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 46 × 62? (a) 30000 (b) 300 (c) 3000
  11. 11.Best estimate of 90 × 41? (a) 36000 (b) 3600 (c) 360
  12. 12.Best estimate of 76 × 51? (a) 400 (b) 4000 (c) 40000
  13. 13.Best estimate of 76 × 37? (a) 3200 (b) 32000 (c) 320
  14. 14.Best estimate of 596 + 662? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 48 × 97? (a) 5000 (b) 50000 (c) 500
  16. 16.Best estimate of 42 × 58? (a) 24000 (b) 240 (c) 2400
  17. 17.Best estimate of 76 × 76? (a) 6400 (b) 640 (c) 64000
  18. 18.Best estimate of 64 × 29? (a) 1800 (b) 180 (c) 18000
  19. 19.Best estimate of 64 × 63? (a) 36000 (b) 3600 (c) 360
  20. 20.Best estimate of 183 + 436? (a) 400 (b) 600 (c) 800
  21. 21.Best estimate of 315 + 702? (a) 800 (b) 1000 (c) 1200
  22. 22.Best estimate of 87 × 20? (a) 1800 (b) 180 (c) 18000
  23. 23.Best estimate of 338 + 299? (a) 800 (b) 400 (c) 600
  24. 24.Best estimate of 306 + 480? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 92 × 22? (a) 180 (b) 1800 (c) 18000
  26. 26.Best estimate of 19 × 78? (a) 1600 (b) 160 (c) 16000
  27. 27.Best estimate of 60 × 88? (a) 5400 (b) 54000 (c) 540
  28. 28.Best estimate of 346 + 373? (a) 700 (b) 900 (c) 500
  29. 29.Best estimate of 41 × 14? (a) 40 (b) 400 (c) 4000
  30. 30.Best estimate of 636 + 867? (a) 1500 (b) 1700 (c) 1300
  31. 31.Best estimate of 13 × 71? (a) 700 (b) 70 (c) 7000
  32. 32.Best estimate of 441 + 382? (a) 600 (b) 1000 (c) 800
  33. 33.Best estimate of 83 × 94? (a) 72000 (b) 7200 (c) 720
  34. 34.Best estimate of 93 × 66? (a) 6300 (b) 63000 (c) 630
  35. 35.Best estimate of 448 + 461? (a) 900 (b) 700 (c) 1100
  36. 36.Best estimate of 19 × 19? (a) 40 (b) 400 (c) 4000
  37. 37.Best estimate of 162 + 322? (a) 500 (b) 300 (c) 700
  38. 38.Best estimate of 218 + 298? (a) 500 (b) 300 (c) 700
  39. 39.Best estimate of 544 + 353? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 254 + 830? (a) 900 (b) 1100 (c) 1300

Answer key

  1. 4800
  2. 1400
  3. 4000
  4. 2000
  5. 4500
  6. 4200
  7. 1200
  8. 300
  9. 1200
  10. 3000
  11. 3600
  12. 4000
  13. 3200
  14. 1300
  15. 5000
  16. 2400
  17. 6400
  18. 1800
  19. 3600
  20. 600
  21. 1000
  22. 1800
  23. 600
  24. 800
  25. 1800
  26. 1600
  27. 5400
  28. 700
  29. 400
  30. 1500
  31. 700
  32. 800
  33. 7200
  34. 6300
  35. 900
  36. 400
  37. 500
  38. 500
  39. 900
  40. 1100

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