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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 632 · 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 86 × 17? (a) 180 (b) 18000 (c) 1800
  2. 2.Best estimate of 535 + 758? (a) 1300 (b) 1100 (c) 1500
  3. 3.Best estimate of 291 + 641? (a) 700 (b) 900 (c) 1100
  4. 4.Best estimate of 169 + 311? (a) 500 (b) 300 (c) 700
  5. 5.Best estimate of 63 × 74? (a) 42000 (b) 4200 (c) 420
  6. 6.Best estimate of 51 × 36? (a) 200 (b) 2000 (c) 20000
  7. 7.Best estimate of 30 × 28? (a) 900 (b) 9000 (c) 90
  8. 8.Best estimate of 14 × 46? (a) 500 (b) 5000 (c) 50
  9. 9.Best estimate of 657 + 763? (a) 1700 (b) 1500 (c) 1300
  10. 10.Best estimate of 224 + 323? (a) 300 (b) 500 (c) 700
  11. 11.Best estimate of 580 + 149? (a) 900 (b) 700 (c) 500
  12. 12.Best estimate of 162 + 286? (a) 300 (b) 700 (c) 500
  13. 13.Best estimate of 53 × 68? (a) 35000 (b) 350 (c) 3500
  14. 14.Best estimate of 507 + 277? (a) 800 (b) 600 (c) 1000
  15. 15.Best estimate of 261 + 833? (a) 1300 (b) 1100 (c) 900
  16. 16.Best estimate of 61 × 50? (a) 300 (b) 3000 (c) 30000
  17. 17.Best estimate of 17 × 54? (a) 100 (b) 10000 (c) 1000
  18. 18.Best estimate of 715 + 247? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 23 × 22? (a) 400 (b) 40 (c) 4000
  20. 20.Best estimate of 618 + 363? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 666 + 124? (a) 800 (b) 1000 (c) 600
  22. 22.Best estimate of 302 + 203? (a) 500 (b) 700 (c) 300
  23. 23.Best estimate of 77 × 88? (a) 720 (b) 72000 (c) 7200
  24. 24.Best estimate of 376 + 661? (a) 1100 (b) 1300 (c) 900
  25. 25.Best estimate of 59 × 94? (a) 54000 (b) 540 (c) 5400
  26. 26.Best estimate of 30 × 23? (a) 60 (b) 600 (c) 6000
  27. 27.Best estimate of 527 + 293? (a) 800 (b) 600 (c) 1000
  28. 28.Best estimate of 495 + 704? (a) 1400 (b) 1200 (c) 1000
  29. 29.Best estimate of 21 × 17? (a) 4000 (b) 40 (c) 400
  30. 30.Best estimate of 241 + 543? (a) 700 (b) 500 (c) 900
  31. 31.Best estimate of 267 + 697? (a) 1000 (b) 800 (c) 1200
  32. 32.Best estimate of 209 + 257? (a) 500 (b) 700 (c) 300
  33. 33.Best estimate of 96 × 37? (a) 40000 (b) 4000 (c) 400
  34. 34.Best estimate of 167 + 749? (a) 1100 (b) 900 (c) 700
  35. 35.Best estimate of 709 + 360? (a) 1300 (b) 900 (c) 1100
  36. 36.Best estimate of 494 + 673? (a) 1400 (b) 1000 (c) 1200
  37. 37.Best estimate of 526 + 593? (a) 1300 (b) 900 (c) 1100
  38. 38.Best estimate of 72 × 49? (a) 35000 (b) 3500 (c) 350
  39. 39.Best estimate of 73 × 66? (a) 490 (b) 49000 (c) 4900
  40. 40.Best estimate of 30 × 33? (a) 9000 (b) 90 (c) 900

Answer key

  1. 1800
  2. 1300
  3. 900
  4. 500
  5. 4200
  6. 2000
  7. 900
  8. 500
  9. 1500
  10. 500
  11. 700
  12. 500
  13. 3500
  14. 800
  15. 1100
  16. 3000
  17. 1000
  18. 900
  19. 400
  20. 1000
  21. 800
  22. 500
  23. 7200
  24. 1100
  25. 5400
  26. 600
  27. 800
  28. 1200
  29. 400
  30. 700
  31. 1000
  32. 500
  33. 4000
  34. 900
  35. 1100
  36. 1200
  37. 1100
  38. 3500
  39. 4900
  40. 900

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