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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 843 · 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 31 × 86? (a) 270 (b) 2700 (c) 27000
  2. 2.Best estimate of 36 × 66? (a) 28000 (b) 280 (c) 2800
  3. 3.Best estimate of 30 × 21? (a) 6000 (b) 600 (c) 60
  4. 4.Best estimate of 23 × 98? (a) 2000 (b) 200 (c) 20000
  5. 5.Best estimate of 97 × 19? (a) 2000 (b) 20000 (c) 200
  6. 6.Best estimate of 76 × 84? (a) 64000 (b) 6400 (c) 640
  7. 7.Best estimate of 715 + 422? (a) 1300 (b) 900 (c) 1100
  8. 8.Best estimate of 66 × 76? (a) 5600 (b) 56000 (c) 560
  9. 9.Best estimate of 97 × 73? (a) 700 (b) 70000 (c) 7000
  10. 10.Best estimate of 223 + 689? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 849 + 286? (a) 1300 (b) 900 (c) 1100
  12. 12.Best estimate of 12 × 47? (a) 500 (b) 50 (c) 5000
  13. 13.Best estimate of 13 × 90? (a) 90 (b) 900 (c) 9000
  14. 14.Best estimate of 372 + 246? (a) 600 (b) 800 (c) 400
  15. 15.Best estimate of 714 + 761? (a) 1500 (b) 1300 (c) 1700
  16. 16.Best estimate of 92 × 81? (a) 720 (b) 72000 (c) 7200
  17. 17.Best estimate of 47 × 83? (a) 4000 (b) 400 (c) 40000
  18. 18.Best estimate of 697 + 149? (a) 800 (b) 600 (c) 1000
  19. 19.Best estimate of 23 × 16? (a) 40 (b) 400 (c) 4000
  20. 20.Best estimate of 544 + 366? (a) 700 (b) 900 (c) 1100
  21. 21.Best estimate of 262 + 187? (a) 300 (b) 700 (c) 500
  22. 22.Best estimate of 97 × 36? (a) 4000 (b) 400 (c) 40000
  23. 23.Best estimate of 21 × 23? (a) 400 (b) 4000 (c) 40
  24. 24.Best estimate of 58 × 86? (a) 5400 (b) 54000 (c) 540
  25. 25.Best estimate of 14 × 22? (a) 200 (b) 20 (c) 2000
  26. 26.Best estimate of 749 + 329? (a) 800 (b) 1000 (c) 1200
  27. 27.Best estimate of 66 × 67? (a) 4900 (b) 490 (c) 49000
  28. 28.Best estimate of 67 × 16? (a) 140 (b) 14000 (c) 1400
  29. 29.Best estimate of 98 × 41? (a) 4000 (b) 40000 (c) 400
  30. 30.Best estimate of 516 + 234? (a) 900 (b) 700 (c) 500
  31. 31.Best estimate of 13 × 29? (a) 3000 (b) 30 (c) 300
  32. 32.Best estimate of 84 × 36? (a) 32000 (b) 3200 (c) 320
  33. 33.Best estimate of 44 × 26? (a) 1200 (b) 12000 (c) 120
  34. 34.Best estimate of 460 + 275? (a) 600 (b) 800 (c) 1000
  35. 35.Best estimate of 421 + 430? (a) 800 (b) 600 (c) 1000
  36. 36.Best estimate of 19 × 54? (a) 100 (b) 1000 (c) 10000
  37. 37.Best estimate of 71 × 76? (a) 560 (b) 56000 (c) 5600
  38. 38.Best estimate of 426 + 382? (a) 800 (b) 1000 (c) 600
  39. 39.Best estimate of 38 × 46? (a) 2000 (b) 200 (c) 20000
  40. 40.Best estimate of 26 × 91? (a) 2700 (b) 27000 (c) 270

Answer key

  1. 2700
  2. 2800
  3. 600
  4. 2000
  5. 2000
  6. 6400
  7. 1100
  8. 5600
  9. 7000
  10. 900
  11. 1100
  12. 500
  13. 900
  14. 600
  15. 1500
  16. 7200
  17. 4000
  18. 800
  19. 400
  20. 900
  21. 500
  22. 4000
  23. 400
  24. 5400
  25. 200
  26. 1000
  27. 4900
  28. 1400
  29. 4000
  30. 700
  31. 300
  32. 3200
  33. 1200
  34. 800
  35. 800
  36. 1000
  37. 5600
  38. 800
  39. 2000
  40. 2700

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