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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 233 · 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 × 71? (a) 6300 (b) 63000 (c) 630
  2. 2.Best estimate of 509 + 446? (a) 900 (b) 700 (c) 1100
  3. 3.Best estimate of 56 × 26? (a) 18000 (b) 1800 (c) 180
  4. 4.Best estimate of 633 + 545? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 489 + 134? (a) 800 (b) 600 (c) 400
  6. 6.Best estimate of 24 × 16? (a) 4000 (b) 400 (c) 40
  7. 7.Best estimate of 216 + 467? (a) 500 (b) 700 (c) 900
  8. 8.Best estimate of 299 + 164? (a) 300 (b) 500 (c) 700
  9. 9.Best estimate of 57 × 64? (a) 360 (b) 36000 (c) 3600
  10. 10.Best estimate of 83 × 59? (a) 480 (b) 48000 (c) 4800
  11. 11.Best estimate of 538 + 473? (a) 800 (b) 1000 (c) 1200
  12. 12.Best estimate of 21 × 34? (a) 600 (b) 6000 (c) 60
  13. 13.Best estimate of 840 + 605? (a) 1400 (b) 1600 (c) 1200
  14. 14.Best estimate of 768 + 766? (a) 1800 (b) 1400 (c) 1600
  15. 15.Best estimate of 501 + 808? (a) 1500 (b) 1100 (c) 1300
  16. 16.Best estimate of 76 × 16? (a) 1600 (b) 160 (c) 16000
  17. 17.Best estimate of 34 × 19? (a) 60 (b) 6000 (c) 600
  18. 18.Best estimate of 328 + 857? (a) 1400 (b) 1000 (c) 1200
  19. 19.Best estimate of 61 × 82? (a) 48000 (b) 4800 (c) 480
  20. 20.Best estimate of 82 × 97? (a) 80000 (b) 800 (c) 8000
  21. 21.Best estimate of 26 × 77? (a) 24000 (b) 240 (c) 2400
  22. 22.Best estimate of 28 × 18? (a) 60 (b) 600 (c) 6000
  23. 23.Best estimate of 724 + 129? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 68 × 34? (a) 210 (b) 2100 (c) 21000
  25. 25.Best estimate of 706 + 513? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 86 × 46? (a) 4500 (b) 45000 (c) 450
  27. 27.Best estimate of 472 + 668? (a) 1200 (b) 1000 (c) 1400
  28. 28.Best estimate of 444 + 555? (a) 1200 (b) 1000 (c) 800
  29. 29.Best estimate of 14 × 36? (a) 40 (b) 400 (c) 4000
  30. 30.Best estimate of 381 + 691? (a) 1300 (b) 1100 (c) 900
  31. 31.Best estimate of 863 + 292? (a) 1200 (b) 1000 (c) 1400
  32. 32.Best estimate of 820 + 754? (a) 1800 (b) 1400 (c) 1600
  33. 33.Best estimate of 551 + 857? (a) 1700 (b) 1500 (c) 1300
  34. 34.Best estimate of 66 × 66? (a) 49000 (b) 490 (c) 4900
  35. 35.Best estimate of 370 + 145? (a) 500 (b) 300 (c) 700
  36. 36.Best estimate of 528 + 757? (a) 1500 (b) 1300 (c) 1100
  37. 37.Best estimate of 394 + 337? (a) 900 (b) 500 (c) 700
  38. 38.Best estimate of 66 × 81? (a) 5600 (b) 56000 (c) 560
  39. 39.Best estimate of 827 + 651? (a) 1300 (b) 1700 (c) 1500
  40. 40.Best estimate of 79 × 32? (a) 24000 (b) 2400 (c) 240

Answer key

  1. 6300
  2. 900
  3. 1800
  4. 1100
  5. 600
  6. 400
  7. 700
  8. 500
  9. 3600
  10. 4800
  11. 1000
  12. 600
  13. 1400
  14. 1600
  15. 1300
  16. 1600
  17. 600
  18. 1200
  19. 4800
  20. 8000
  21. 2400
  22. 600
  23. 800
  24. 2100
  25. 1200
  26. 4500
  27. 1200
  28. 1000
  29. 400
  30. 1100
  31. 1200
  32. 1600
  33. 1500
  34. 4900
  35. 500
  36. 1300
  37. 700
  38. 5600
  39. 1500
  40. 2400

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