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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 239 · 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 74 × 40? (a) 28000 (b) 2800 (c) 280
  2. 2.Best estimate of 49 × 21? (a) 100 (b) 10000 (c) 1000
  3. 3.Best estimate of 133 + 464? (a) 800 (b) 400 (c) 600
  4. 4.Best estimate of 13 × 41? (a) 4000 (b) 40 (c) 400
  5. 5.Best estimate of 37 × 17? (a) 800 (b) 80 (c) 8000
  6. 6.Best estimate of 96 × 32? (a) 3000 (b) 300 (c) 30000
  7. 7.Best estimate of 13 × 23? (a) 200 (b) 20 (c) 2000
  8. 8.Best estimate of 48 × 80? (a) 4000 (b) 400 (c) 40000
  9. 9.Best estimate of 56 × 81? (a) 48000 (b) 480 (c) 4800
  10. 10.Best estimate of 42 × 36? (a) 160 (b) 1600 (c) 16000
  11. 11.Best estimate of 144 + 531? (a) 400 (b) 600 (c) 800
  12. 12.Best estimate of 524 + 496? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 17 × 16? (a) 400 (b) 40 (c) 4000
  14. 14.Best estimate of 484 + 778? (a) 1100 (b) 1300 (c) 1500
  15. 15.Best estimate of 40 × 86? (a) 360 (b) 36000 (c) 3600
  16. 16.Best estimate of 20 × 73? (a) 140 (b) 14000 (c) 1400
  17. 17.Best estimate of 796 + 388? (a) 1000 (b) 1200 (c) 1400
  18. 18.Best estimate of 76 × 62? (a) 48000 (b) 480 (c) 4800
  19. 19.Best estimate of 39 × 54? (a) 2000 (b) 200 (c) 20000
  20. 20.Best estimate of 32 × 27? (a) 900 (b) 90 (c) 9000
  21. 21.Best estimate of 261 + 711? (a) 1200 (b) 800 (c) 1000
  22. 22.Best estimate of 51 × 86? (a) 450 (b) 4500 (c) 45000
  23. 23.Best estimate of 57 × 26? (a) 18000 (b) 1800 (c) 180
  24. 24.Best estimate of 222 + 581? (a) 800 (b) 1000 (c) 600
  25. 25.Best estimate of 655 + 547? (a) 1200 (b) 1400 (c) 1000
  26. 26.Best estimate of 88 × 16? (a) 180 (b) 18000 (c) 1800
  27. 27.Best estimate of 31 × 27? (a) 900 (b) 90 (c) 9000
  28. 28.Best estimate of 173 + 813? (a) 1200 (b) 800 (c) 1000
  29. 29.Best estimate of 246 + 819? (a) 1200 (b) 800 (c) 1000
  30. 30.Best estimate of 84 × 37? (a) 3200 (b) 320 (c) 32000
  31. 31.Best estimate of 14 × 60? (a) 6000 (b) 60 (c) 600
  32. 32.Best estimate of 76 × 28? (a) 2400 (b) 240 (c) 24000
  33. 33.Best estimate of 57 × 52? (a) 30000 (b) 3000 (c) 300
  34. 34.Best estimate of 87 × 63? (a) 5400 (b) 54000 (c) 540
  35. 35.Best estimate of 16 × 98? (a) 200 (b) 20000 (c) 2000
  36. 36.Best estimate of 43 × 60? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 78 × 80? (a) 6400 (b) 64000 (c) 640
  38. 38.Best estimate of 192 + 834? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 672 + 125? (a) 600 (b) 800 (c) 1000
  40. 40.Best estimate of 345 + 836? (a) 1300 (b) 1100 (c) 900

Answer key

  1. 2800
  2. 1000
  3. 600
  4. 400
  5. 800
  6. 3000
  7. 200
  8. 4000
  9. 4800
  10. 1600
  11. 600
  12. 1000
  13. 400
  14. 1300
  15. 3600
  16. 1400
  17. 1200
  18. 4800
  19. 2000
  20. 900
  21. 1000
  22. 4500
  23. 1800
  24. 800
  25. 1200
  26. 1800
  27. 900
  28. 1000
  29. 1000
  30. 3200
  31. 600
  32. 2400
  33. 3000
  34. 5400
  35. 2000
  36. 2400
  37. 6400
  38. 1000
  39. 800
  40. 1100

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