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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 104 · 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 512 + 813? (a) 1100 (b) 1500 (c) 1300
  2. 2.Best estimate of 329 + 823? (a) 1100 (b) 900 (c) 1300
  3. 3.Best estimate of 34 × 78? (a) 240 (b) 2400 (c) 24000
  4. 4.Best estimate of 86 × 76? (a) 7200 (b) 72000 (c) 720
  5. 5.Best estimate of 48 × 46? (a) 2500 (b) 25000 (c) 250
  6. 6.Best estimate of 727 + 262? (a) 1200 (b) 1000 (c) 800
  7. 7.Best estimate of 72 × 57? (a) 4200 (b) 42000 (c) 420
  8. 8.Best estimate of 12 × 20? (a) 20 (b) 2000 (c) 200
  9. 9.Best estimate of 87 × 33? (a) 27000 (b) 270 (c) 2700
  10. 10.Best estimate of 76 × 68? (a) 56000 (b) 5600 (c) 560
  11. 11.Best estimate of 283 + 231? (a) 500 (b) 700 (c) 300
  12. 12.Best estimate of 406 + 382? (a) 800 (b) 1000 (c) 600
  13. 13.Best estimate of 66 × 89? (a) 6300 (b) 630 (c) 63000
  14. 14.Best estimate of 77 × 66? (a) 56000 (b) 5600 (c) 560
  15. 15.Best estimate of 61 × 29? (a) 18000 (b) 180 (c) 1800
  16. 16.Best estimate of 49 × 77? (a) 40000 (b) 4000 (c) 400
  17. 17.Best estimate of 16 × 60? (a) 12000 (b) 120 (c) 1200
  18. 18.Best estimate of 21 × 29? (a) 6000 (b) 60 (c) 600
  19. 19.Best estimate of 18 × 49? (a) 10000 (b) 1000 (c) 100
  20. 20.Best estimate of 22 × 29? (a) 600 (b) 60 (c) 6000
  21. 21.Best estimate of 59 × 36? (a) 240 (b) 24000 (c) 2400
  22. 22.Best estimate of 228 + 195? (a) 600 (b) 200 (c) 400
  23. 23.Best estimate of 56 × 94? (a) 5400 (b) 54000 (c) 540
  24. 24.Best estimate of 210 + 281? (a) 500 (b) 300 (c) 700
  25. 25.Best estimate of 720 + 592? (a) 1100 (b) 1500 (c) 1300
  26. 26.Best estimate of 19 × 62? (a) 1200 (b) 12000 (c) 120
  27. 27.Best estimate of 12 × 84? (a) 800 (b) 80 (c) 8000
  28. 28.Best estimate of 213 + 129? (a) 100 (b) 500 (c) 300
  29. 29.Best estimate of 21 × 22? (a) 40 (b) 400 (c) 4000
  30. 30.Best estimate of 141 + 586? (a) 700 (b) 500 (c) 900
  31. 31.Best estimate of 851 + 857? (a) 1600 (b) 1800 (c) 2000
  32. 32.Best estimate of 756 + 542? (a) 1100 (b) 1500 (c) 1300
  33. 33.Best estimate of 38 × 90? (a) 360 (b) 36000 (c) 3600
  34. 34.Best estimate of 83 × 94? (a) 720 (b) 72000 (c) 7200
  35. 35.Best estimate of 520 + 574? (a) 1100 (b) 1300 (c) 900
  36. 36.Best estimate of 71 × 79? (a) 560 (b) 5600 (c) 56000
  37. 37.Best estimate of 796 + 360? (a) 1400 (b) 1200 (c) 1000
  38. 38.Best estimate of 600 + 294? (a) 1100 (b) 700 (c) 900
  39. 39.Best estimate of 434 + 134? (a) 500 (b) 300 (c) 700
  40. 40.Best estimate of 48 × 92? (a) 450 (b) 45000 (c) 4500

Answer key

  1. 1300
  2. 1100
  3. 2400
  4. 7200
  5. 2500
  6. 1000
  7. 4200
  8. 200
  9. 2700
  10. 5600
  11. 500
  12. 800
  13. 6300
  14. 5600
  15. 1800
  16. 4000
  17. 1200
  18. 600
  19. 1000
  20. 600
  21. 2400
  22. 400
  23. 5400
  24. 500
  25. 1300
  26. 1200
  27. 800
  28. 300
  29. 400
  30. 700
  31. 1800
  32. 1300
  33. 3600
  34. 7200
  35. 1100
  36. 5600
  37. 1200
  38. 900
  39. 500
  40. 4500

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