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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 199 · 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 21 × 20? (a) 4000 (b) 400 (c) 40
  2. 2.Best estimate of 636 + 715? (a) 1500 (b) 1300 (c) 1100
  3. 3.Best estimate of 412 + 425? (a) 600 (b) 800 (c) 1000
  4. 4.Best estimate of 76 × 74? (a) 56000 (b) 5600 (c) 560
  5. 5.Best estimate of 32 × 96? (a) 300 (b) 30000 (c) 3000
  6. 6.Best estimate of 23 × 53? (a) 1000 (b) 10000 (c) 100
  7. 7.Best estimate of 359 + 176? (a) 800 (b) 600 (c) 400
  8. 8.Best estimate of 388 + 154? (a) 800 (b) 600 (c) 400
  9. 9.Best estimate of 18 × 21? (a) 400 (b) 40 (c) 4000
  10. 10.Best estimate of 82 × 61? (a) 48000 (b) 4800 (c) 480
  11. 11.Best estimate of 643 + 405? (a) 1000 (b) 1200 (c) 800
  12. 12.Best estimate of 70 × 71? (a) 49000 (b) 4900 (c) 490
  13. 13.Best estimate of 447 + 710? (a) 1100 (b) 900 (c) 1300
  14. 14.Best estimate of 864 + 834? (a) 1900 (b) 1700 (c) 1500
  15. 15.Best estimate of 355 + 860? (a) 1100 (b) 1500 (c) 1300
  16. 16.Best estimate of 691 + 867? (a) 1600 (b) 1400 (c) 1800
  17. 17.Best estimate of 633 + 809? (a) 1200 (b) 1400 (c) 1600
  18. 18.Best estimate of 26 × 16? (a) 60 (b) 600 (c) 6000
  19. 19.Best estimate of 49 × 72? (a) 3500 (b) 350 (c) 35000
  20. 20.Best estimate of 861 + 654? (a) 1400 (b) 1600 (c) 1800
  21. 21.Best estimate of 16 × 82? (a) 16000 (b) 160 (c) 1600
  22. 22.Best estimate of 737 + 289? (a) 800 (b) 1200 (c) 1000
  23. 23.Best estimate of 458 + 861? (a) 1600 (b) 1200 (c) 1400
  24. 24.Best estimate of 62 × 77? (a) 4800 (b) 48000 (c) 480
  25. 25.Best estimate of 492 + 131? (a) 400 (b) 600 (c) 800
  26. 26.Best estimate of 66 × 36? (a) 2800 (b) 28000 (c) 280
  27. 27.Best estimate of 361 + 304? (a) 700 (b) 900 (c) 500
  28. 28.Best estimate of 671 + 811? (a) 1300 (b) 1700 (c) 1500
  29. 29.Best estimate of 235 + 832? (a) 1200 (b) 800 (c) 1000
  30. 30.Best estimate of 46 × 83? (a) 400 (b) 4000 (c) 40000
  31. 31.Best estimate of 98 × 54? (a) 50000 (b) 500 (c) 5000
  32. 32.Best estimate of 541 + 398? (a) 700 (b) 1100 (c) 900
  33. 33.Best estimate of 311 + 798? (a) 1100 (b) 1300 (c) 900
  34. 34.Best estimate of 754 + 707? (a) 1700 (b) 1500 (c) 1300
  35. 35.Best estimate of 393 + 167? (a) 400 (b) 800 (c) 600
  36. 36.Best estimate of 88 × 67? (a) 6300 (b) 63000 (c) 630
  37. 37.Best estimate of 459 + 259? (a) 1000 (b) 600 (c) 800
  38. 38.Best estimate of 183 + 535? (a) 900 (b) 700 (c) 500
  39. 39.Best estimate of 92 × 58? (a) 540 (b) 54000 (c) 5400
  40. 40.Best estimate of 34 × 34? (a) 900 (b) 9000 (c) 90

Answer key

  1. 400
  2. 1300
  3. 800
  4. 5600
  5. 3000
  6. 1000
  7. 600
  8. 600
  9. 400
  10. 4800
  11. 1000
  12. 4900
  13. 1100
  14. 1700
  15. 1300
  16. 1600
  17. 1400
  18. 600
  19. 3500
  20. 1600
  21. 1600
  22. 1000
  23. 1400
  24. 4800
  25. 600
  26. 2800
  27. 700
  28. 1500
  29. 1000
  30. 4000
  31. 5000
  32. 900
  33. 1100
  34. 1500
  35. 600
  36. 6300
  37. 800
  38. 700
  39. 5400
  40. 900

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