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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 128 · 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 12 × 46? (a) 500 (b) 5000 (c) 50
  2. 2.Best estimate of 73 × 86? (a) 630 (b) 6300 (c) 63000
  3. 3.Best estimate of 274 + 641? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 82 × 63? (a) 480 (b) 4800 (c) 48000
  5. 5.Best estimate of 197 + 696? (a) 1100 (b) 700 (c) 900
  6. 6.Best estimate of 636 + 526? (a) 1100 (b) 1300 (c) 900
  7. 7.Best estimate of 91 × 54? (a) 4500 (b) 450 (c) 45000
  8. 8.Best estimate of 299 + 188? (a) 500 (b) 700 (c) 300
  9. 9.Best estimate of 701 + 740? (a) 1200 (b) 1400 (c) 1600
  10. 10.Best estimate of 86 × 64? (a) 54000 (b) 5400 (c) 540
  11. 11.Best estimate of 56 × 21? (a) 120 (b) 1200 (c) 12000
  12. 12.Best estimate of 89 × 33? (a) 27000 (b) 2700 (c) 270
  13. 13.Best estimate of 21 × 38? (a) 8000 (b) 80 (c) 800
  14. 14.Best estimate of 70 × 27? (a) 21000 (b) 2100 (c) 210
  15. 15.Best estimate of 504 + 487? (a) 800 (b) 1200 (c) 1000
  16. 16.Best estimate of 326 + 231? (a) 300 (b) 700 (c) 500
  17. 17.Best estimate of 641 + 311? (a) 1100 (b) 700 (c) 900
  18. 18.Best estimate of 580 + 408? (a) 800 (b) 1000 (c) 1200
  19. 19.Best estimate of 141 + 763? (a) 1100 (b) 900 (c) 700
  20. 20.Best estimate of 848 + 545? (a) 1300 (b) 1100 (c) 1500
  21. 21.Best estimate of 720 + 535? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 791 + 168? (a) 1000 (b) 1200 (c) 800
  23. 23.Best estimate of 825 + 674? (a) 1500 (b) 1300 (c) 1700
  24. 24.Best estimate of 73 × 51? (a) 35000 (b) 3500 (c) 350
  25. 25.Best estimate of 293 + 247? (a) 300 (b) 500 (c) 700
  26. 26.Best estimate of 36 × 24? (a) 800 (b) 80 (c) 8000
  27. 27.Best estimate of 32 × 28? (a) 90 (b) 900 (c) 9000
  28. 28.Best estimate of 22 × 30? (a) 60 (b) 600 (c) 6000
  29. 29.Best estimate of 353 + 289? (a) 900 (b) 500 (c) 700
  30. 30.Best estimate of 20 × 82? (a) 16000 (b) 1600 (c) 160
  31. 31.Best estimate of 16 × 27? (a) 6000 (b) 60 (c) 600
  32. 32.Best estimate of 26 × 93? (a) 27000 (b) 270 (c) 2700
  33. 33.Best estimate of 98 × 36? (a) 400 (b) 40000 (c) 4000
  34. 34.Best estimate of 276 + 827? (a) 1300 (b) 900 (c) 1100
  35. 35.Best estimate of 176 + 419? (a) 800 (b) 600 (c) 400
  36. 36.Best estimate of 551 + 742? (a) 1100 (b) 1500 (c) 1300
  37. 37.Best estimate of 30 × 46? (a) 1500 (b) 15000 (c) 150
  38. 38.Best estimate of 12 × 40? (a) 4000 (b) 40 (c) 400
  39. 39.Best estimate of 404 + 257? (a) 700 (b) 900 (c) 500
  40. 40.Best estimate of 62 × 54? (a) 300 (b) 30000 (c) 3000

Answer key

  1. 500
  2. 6300
  3. 900
  4. 4800
  5. 900
  6. 1100
  7. 4500
  8. 500
  9. 1400
  10. 5400
  11. 1200
  12. 2700
  13. 800
  14. 2100
  15. 1000
  16. 500
  17. 900
  18. 1000
  19. 900
  20. 1300
  21. 1200
  22. 1000
  23. 1500
  24. 3500
  25. 500
  26. 800
  27. 900
  28. 600
  29. 700
  30. 1600
  31. 600
  32. 2700
  33. 4000
  34. 1100
  35. 600
  36. 1300
  37. 1500
  38. 400
  39. 700
  40. 3000

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