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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 655 · 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 92 × 82? (a) 7200 (b) 720 (c) 72000
  2. 2.Best estimate of 82 × 72? (a) 5600 (b) 56000 (c) 560
  3. 3.Best estimate of 536 + 297? (a) 800 (b) 1000 (c) 600
  4. 4.Best estimate of 54 × 97? (a) 50000 (b) 500 (c) 5000
  5. 5.Best estimate of 41 × 39? (a) 160 (b) 16000 (c) 1600
  6. 6.Best estimate of 174 + 251? (a) 500 (b) 700 (c) 300
  7. 7.Best estimate of 148 + 309? (a) 400 (b) 600 (c) 200
  8. 8.Best estimate of 76 × 87? (a) 72000 (b) 720 (c) 7200
  9. 9.Best estimate of 260 + 375? (a) 900 (b) 700 (c) 500
  10. 10.Best estimate of 23 × 51? (a) 100 (b) 1000 (c) 10000
  11. 11.Best estimate of 73 × 80? (a) 5600 (b) 560 (c) 56000
  12. 12.Best estimate of 61 × 19? (a) 12000 (b) 1200 (c) 120
  13. 13.Best estimate of 36 × 71? (a) 28000 (b) 2800 (c) 280
  14. 14.Best estimate of 30 × 70? (a) 210 (b) 2100 (c) 21000
  15. 15.Best estimate of 86 × 70? (a) 6300 (b) 63000 (c) 630
  16. 16.Best estimate of 122 + 321? (a) 400 (b) 200 (c) 600
  17. 17.Best estimate of 610 + 366? (a) 800 (b) 1000 (c) 1200
  18. 18.Best estimate of 163 + 466? (a) 500 (b) 900 (c) 700
  19. 19.Best estimate of 64 × 83? (a) 48000 (b) 480 (c) 4800
  20. 20.Best estimate of 333 + 862? (a) 1200 (b) 1000 (c) 1400
  21. 21.Best estimate of 79 × 49? (a) 400 (b) 4000 (c) 40000
  22. 22.Best estimate of 210 + 583? (a) 600 (b) 800 (c) 1000
  23. 23.Best estimate of 14 × 41? (a) 400 (b) 4000 (c) 40
  24. 24.Best estimate of 66 × 80? (a) 560 (b) 56000 (c) 5600
  25. 25.Best estimate of 334 + 636? (a) 1100 (b) 900 (c) 700
  26. 26.Best estimate of 579 + 845? (a) 1400 (b) 1600 (c) 1200
  27. 27.Best estimate of 490 + 749? (a) 1000 (b) 1400 (c) 1200
  28. 28.Best estimate of 174 + 808? (a) 800 (b) 1200 (c) 1000
  29. 29.Best estimate of 27 × 47? (a) 150 (b) 1500 (c) 15000
  30. 30.Best estimate of 285 + 121? (a) 600 (b) 200 (c) 400
  31. 31.Best estimate of 486 + 611? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 36 × 73? (a) 2800 (b) 28000 (c) 280
  33. 33.Best estimate of 194 + 421? (a) 400 (b) 600 (c) 800
  34. 34.Best estimate of 584 + 405? (a) 1000 (b) 1200 (c) 800
  35. 35.Best estimate of 40 × 18? (a) 800 (b) 8000 (c) 80
  36. 36.Best estimate of 13 × 49? (a) 50 (b) 5000 (c) 500
  37. 37.Best estimate of 561 + 427? (a) 800 (b) 1000 (c) 1200
  38. 38.Best estimate of 36 × 70? (a) 280 (b) 2800 (c) 28000
  39. 39.Best estimate of 31 × 84? (a) 240 (b) 24000 (c) 2400
  40. 40.Best estimate of 58 × 54? (a) 300 (b) 30000 (c) 3000

Answer key

  1. 7200
  2. 5600
  3. 800
  4. 5000
  5. 1600
  6. 500
  7. 400
  8. 7200
  9. 700
  10. 1000
  11. 5600
  12. 1200
  13. 2800
  14. 2100
  15. 6300
  16. 400
  17. 1000
  18. 700
  19. 4800
  20. 1200
  21. 4000
  22. 800
  23. 400
  24. 5600
  25. 900
  26. 1400
  27. 1200
  28. 1000
  29. 1500
  30. 400
  31. 1100
  32. 2800
  33. 600
  34. 1000
  35. 800
  36. 500
  37. 1000
  38. 2800
  39. 2400
  40. 3000

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