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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 644 · 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 568 + 866? (a) 1300 (b) 1500 (c) 1700
  2. 2.Best estimate of 172 + 190? (a) 400 (b) 200 (c) 600
  3. 3.Best estimate of 29 × 20? (a) 6000 (b) 60 (c) 600
  4. 4.Best estimate of 50 × 27? (a) 1500 (b) 150 (c) 15000
  5. 5.Best estimate of 684 + 807? (a) 1500 (b) 1700 (c) 1300
  6. 6.Best estimate of 469 + 683? (a) 1200 (b) 1000 (c) 1400
  7. 7.Best estimate of 22 × 36? (a) 80 (b) 8000 (c) 800
  8. 8.Best estimate of 57 × 22? (a) 120 (b) 1200 (c) 12000
  9. 9.Best estimate of 280 + 312? (a) 800 (b) 600 (c) 400
  10. 10.Best estimate of 121 + 145? (a) 400 (b) 0 (c) 200
  11. 11.Best estimate of 96 × 43? (a) 4000 (b) 40000 (c) 400
  12. 12.Best estimate of 600 + 223? (a) 800 (b) 1000 (c) 600
  13. 13.Best estimate of 82 × 76? (a) 640 (b) 64000 (c) 6400
  14. 14.Best estimate of 298 + 555? (a) 900 (b) 1100 (c) 700
  15. 15.Best estimate of 19 × 89? (a) 18000 (b) 1800 (c) 180
  16. 16.Best estimate of 29 × 61? (a) 1800 (b) 18000 (c) 180
  17. 17.Best estimate of 164 + 754? (a) 1000 (b) 800 (c) 1200
  18. 18.Best estimate of 76 × 82? (a) 64000 (b) 640 (c) 6400
  19. 19.Best estimate of 19 × 66? (a) 140 (b) 1400 (c) 14000
  20. 20.Best estimate of 227 + 725? (a) 700 (b) 900 (c) 1100
  21. 21.Best estimate of 814 + 554? (a) 1400 (b) 1200 (c) 1600
  22. 22.Best estimate of 62 × 12? (a) 6000 (b) 600 (c) 60
  23. 23.Best estimate of 48 × 13? (a) 5000 (b) 50 (c) 500
  24. 24.Best estimate of 751 + 122? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 624 + 217? (a) 800 (b) 1000 (c) 600
  26. 26.Best estimate of 17 × 21? (a) 400 (b) 4000 (c) 40
  27. 27.Best estimate of 80 × 21? (a) 16000 (b) 1600 (c) 160
  28. 28.Best estimate of 139 + 869? (a) 1200 (b) 1000 (c) 800
  29. 29.Best estimate of 62 × 81? (a) 48000 (b) 4800 (c) 480
  30. 30.Best estimate of 129 + 614? (a) 700 (b) 900 (c) 500
  31. 31.Best estimate of 36 × 18? (a) 8000 (b) 800 (c) 80
  32. 32.Best estimate of 847 + 120? (a) 900 (b) 1100 (c) 700
  33. 33.Best estimate of 847 + 568? (a) 1600 (b) 1400 (c) 1200
  34. 34.Best estimate of 53 × 24? (a) 1000 (b) 100 (c) 10000
  35. 35.Best estimate of 224 + 758? (a) 1200 (b) 1000 (c) 800
  36. 36.Best estimate of 599 + 206? (a) 1000 (b) 600 (c) 800
  37. 37.Best estimate of 788 + 121? (a) 900 (b) 700 (c) 1100
  38. 38.Best estimate of 78 × 54? (a) 40000 (b) 400 (c) 4000
  39. 39.Best estimate of 268 + 511? (a) 800 (b) 1000 (c) 600
  40. 40.Best estimate of 534 + 409? (a) 1100 (b) 700 (c) 900

Answer key

  1. 1500
  2. 400
  3. 600
  4. 1500
  5. 1500
  6. 1200
  7. 800
  8. 1200
  9. 600
  10. 200
  11. 4000
  12. 800
  13. 6400
  14. 900
  15. 1800
  16. 1800
  17. 1000
  18. 6400
  19. 1400
  20. 900
  21. 1400
  22. 600
  23. 500
  24. 900
  25. 800
  26. 400
  27. 1600
  28. 1000
  29. 4800
  30. 700
  31. 800
  32. 900
  33. 1400
  34. 1000
  35. 1000
  36. 800
  37. 900
  38. 4000
  39. 800
  40. 900

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