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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 997 · 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 39 × 76? (a) 3200 (b) 32000 (c) 320
  2. 2.Best estimate of 14 × 81? (a) 80 (b) 8000 (c) 800
  3. 3.Best estimate of 684 + 267? (a) 800 (b) 1200 (c) 1000
  4. 4.Best estimate of 426 + 725? (a) 1300 (b) 900 (c) 1100
  5. 5.Best estimate of 54 × 50? (a) 25000 (b) 250 (c) 2500
  6. 6.Best estimate of 507 + 238? (a) 700 (b) 900 (c) 500
  7. 7.Best estimate of 87 × 18? (a) 18000 (b) 1800 (c) 180
  8. 8.Best estimate of 124 + 710? (a) 1000 (b) 800 (c) 600
  9. 9.Best estimate of 90 × 41? (a) 360 (b) 36000 (c) 3600
  10. 10.Best estimate of 96 × 86? (a) 9000 (b) 900 (c) 90000
  11. 11.Best estimate of 495 + 196? (a) 900 (b) 500 (c) 700
  12. 12.Best estimate of 707 + 272? (a) 1200 (b) 800 (c) 1000
  13. 13.Best estimate of 380 + 169? (a) 400 (b) 800 (c) 600
  14. 14.Best estimate of 259 + 352? (a) 700 (b) 900 (c) 500
  15. 15.Best estimate of 500 + 182? (a) 900 (b) 700 (c) 500
  16. 16.Best estimate of 38 × 72? (a) 280 (b) 28000 (c) 2800
  17. 17.Best estimate of 151 + 246? (a) 400 (b) 600 (c) 200
  18. 18.Best estimate of 148 + 531? (a) 600 (b) 400 (c) 800
  19. 19.Best estimate of 781 + 657? (a) 1500 (b) 1700 (c) 1300
  20. 20.Best estimate of 58 × 13? (a) 60 (b) 600 (c) 6000
  21. 21.Best estimate of 17 × 19? (a) 4000 (b) 400 (c) 40
  22. 22.Best estimate of 34 × 41? (a) 12000 (b) 120 (c) 1200
  23. 23.Best estimate of 320 + 292? (a) 600 (b) 800 (c) 400
  24. 24.Best estimate of 86 × 67? (a) 630 (b) 6300 (c) 63000
  25. 25.Best estimate of 424 + 725? (a) 900 (b) 1100 (c) 1300
  26. 26.Best estimate of 548 + 346? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 38 × 26? (a) 12000 (b) 120 (c) 1200
  28. 28.Best estimate of 745 + 426? (a) 900 (b) 1300 (c) 1100
  29. 29.Best estimate of 484 + 673? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 642 + 406? (a) 1200 (b) 1000 (c) 800
  31. 31.Best estimate of 13 × 87? (a) 90 (b) 9000 (c) 900
  32. 32.Best estimate of 426 + 689? (a) 900 (b) 1100 (c) 1300
  33. 33.Best estimate of 37 × 14? (a) 400 (b) 40 (c) 4000
  34. 34.Best estimate of 257 + 421? (a) 700 (b) 500 (c) 900
  35. 35.Best estimate of 341 + 242? (a) 300 (b) 500 (c) 700
  36. 36.Best estimate of 97 × 84? (a) 800 (b) 8000 (c) 80000
  37. 37.Best estimate of 30 × 21? (a) 6000 (b) 600 (c) 60
  38. 38.Best estimate of 475 + 545? (a) 800 (b) 1200 (c) 1000
  39. 39.Best estimate of 67 × 77? (a) 5600 (b) 56000 (c) 560
  40. 40.Best estimate of 457 + 211? (a) 900 (b) 700 (c) 500

Answer key

  1. 3200
  2. 800
  3. 1000
  4. 1100
  5. 2500
  6. 700
  7. 1800
  8. 800
  9. 3600
  10. 9000
  11. 700
  12. 1000
  13. 600
  14. 700
  15. 700
  16. 2800
  17. 400
  18. 600
  19. 1500
  20. 600
  21. 400
  22. 1200
  23. 600
  24. 6300
  25. 1100
  26. 800
  27. 1200
  28. 1100
  29. 1200
  30. 1000
  31. 900
  32. 1100
  33. 400
  34. 700
  35. 500
  36. 8000
  37. 600
  38. 1000
  39. 5600
  40. 700

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