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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 755 · 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 26 × 67? (a) 210 (b) 21000 (c) 2100
  2. 2.Best estimate of 59 × 44? (a) 2400 (b) 24000 (c) 240
  3. 3.Best estimate of 97 × 16? (a) 2000 (b) 20000 (c) 200
  4. 4.Best estimate of 869 + 691? (a) 1600 (b) 1800 (c) 1400
  5. 5.Best estimate of 732 + 552? (a) 1300 (b) 1500 (c) 1100
  6. 6.Best estimate of 677 + 814? (a) 1300 (b) 1700 (c) 1500
  7. 7.Best estimate of 80 × 16? (a) 160 (b) 1600 (c) 16000
  8. 8.Best estimate of 429 + 531? (a) 900 (b) 700 (c) 1100
  9. 9.Best estimate of 868 + 693? (a) 1400 (b) 1600 (c) 1800
  10. 10.Best estimate of 308 + 698? (a) 800 (b) 1200 (c) 1000
  11. 11.Best estimate of 313 + 521? (a) 600 (b) 800 (c) 1000
  12. 12.Best estimate of 69 × 40? (a) 2800 (b) 280 (c) 28000
  13. 13.Best estimate of 51 × 70? (a) 35000 (b) 3500 (c) 350
  14. 14.Best estimate of 89 × 16? (a) 18000 (b) 1800 (c) 180
  15. 15.Best estimate of 37 × 24? (a) 800 (b) 8000 (c) 80
  16. 16.Best estimate of 34 × 13? (a) 3000 (b) 300 (c) 30
  17. 17.Best estimate of 63 × 46? (a) 3000 (b) 300 (c) 30000
  18. 18.Best estimate of 81 × 76? (a) 6400 (b) 64000 (c) 640
  19. 19.Best estimate of 529 + 827? (a) 1300 (b) 1500 (c) 1100
  20. 20.Best estimate of 17 × 12? (a) 2000 (b) 20 (c) 200
  21. 21.Best estimate of 50 × 14? (a) 50 (b) 5000 (c) 500
  22. 22.Best estimate of 24 × 81? (a) 1600 (b) 16000 (c) 160
  23. 23.Best estimate of 36 × 91? (a) 36000 (b) 360 (c) 3600
  24. 24.Best estimate of 53 × 26? (a) 150 (b) 1500 (c) 15000
  25. 25.Best estimate of 763 + 401? (a) 1000 (b) 1400 (c) 1200
  26. 26.Best estimate of 651 + 879? (a) 1400 (b) 1600 (c) 1800
  27. 27.Best estimate of 314 + 652? (a) 1000 (b) 800 (c) 1200
  28. 28.Best estimate of 785 + 388? (a) 1000 (b) 1200 (c) 1400
  29. 29.Best estimate of 651 + 291? (a) 1200 (b) 800 (c) 1000
  30. 30.Best estimate of 56 × 39? (a) 240 (b) 24000 (c) 2400
  31. 31.Best estimate of 576 + 203? (a) 1000 (b) 800 (c) 600
  32. 32.Best estimate of 69 × 36? (a) 2800 (b) 28000 (c) 280
  33. 33.Best estimate of 71 × 16? (a) 14000 (b) 140 (c) 1400
  34. 34.Best estimate of 14 × 87? (a) 90 (b) 9000 (c) 900
  35. 35.Best estimate of 497 + 740? (a) 1000 (b) 1400 (c) 1200
  36. 36.Best estimate of 80 × 71? (a) 5600 (b) 560 (c) 56000
  37. 37.Best estimate of 864 + 607? (a) 1300 (b) 1700 (c) 1500
  38. 38.Best estimate of 54 × 91? (a) 45000 (b) 450 (c) 4500
  39. 39.Best estimate of 447 + 483? (a) 1100 (b) 700 (c) 900
  40. 40.Best estimate of 31 × 82? (a) 24000 (b) 2400 (c) 240

Answer key

  1. 2100
  2. 2400
  3. 2000
  4. 1600
  5. 1300
  6. 1500
  7. 1600
  8. 900
  9. 1600
  10. 1000
  11. 800
  12. 2800
  13. 3500
  14. 1800
  15. 800
  16. 300
  17. 3000
  18. 6400
  19. 1300
  20. 200
  21. 500
  22. 1600
  23. 3600
  24. 1500
  25. 1200
  26. 1600
  27. 1000
  28. 1200
  29. 1000
  30. 2400
  31. 800
  32. 2800
  33. 1400
  34. 900
  35. 1200
  36. 5600
  37. 1500
  38. 4500
  39. 900
  40. 2400

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