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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 67 · 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 620 + 824? (a) 1200 (b) 1600 (c) 1400
  2. 2.Best estimate of 16 × 26? (a) 600 (b) 6000 (c) 60
  3. 3.Best estimate of 84 × 16? (a) 16000 (b) 1600 (c) 160
  4. 4.Best estimate of 20 × 48? (a) 100 (b) 1000 (c) 10000
  5. 5.Best estimate of 771 + 222? (a) 800 (b) 1200 (c) 1000
  6. 6.Best estimate of 408 + 194? (a) 400 (b) 600 (c) 800
  7. 7.Best estimate of 271 + 195? (a) 500 (b) 700 (c) 300
  8. 8.Best estimate of 160 + 712? (a) 900 (b) 1100 (c) 700
  9. 9.Best estimate of 183 + 312? (a) 500 (b) 700 (c) 300
  10. 10.Best estimate of 796 + 794? (a) 1800 (b) 1600 (c) 1400
  11. 11.Best estimate of 158 + 230? (a) 400 (b) 600 (c) 200
  12. 12.Best estimate of 556 + 875? (a) 1500 (b) 1300 (c) 1700
  13. 13.Best estimate of 49 × 14? (a) 500 (b) 50 (c) 5000
  14. 14.Best estimate of 68 × 12? (a) 70 (b) 7000 (c) 700
  15. 15.Best estimate of 14 × 46? (a) 500 (b) 5000 (c) 50
  16. 16.Best estimate of 28 × 86? (a) 2700 (b) 27000 (c) 270
  17. 17.Best estimate of 96 × 57? (a) 6000 (b) 60000 (c) 600
  18. 18.Best estimate of 87 × 66? (a) 6300 (b) 63000 (c) 630
  19. 19.Best estimate of 44 × 48? (a) 2000 (b) 200 (c) 20000
  20. 20.Best estimate of 39 × 66? (a) 28000 (b) 2800 (c) 280
  21. 21.Best estimate of 21 × 82? (a) 160 (b) 16000 (c) 1600
  22. 22.Best estimate of 79 × 16? (a) 160 (b) 1600 (c) 16000
  23. 23.Best estimate of 27 × 28? (a) 900 (b) 90 (c) 9000
  24. 24.Best estimate of 612 + 298? (a) 900 (b) 1100 (c) 700
  25. 25.Best estimate of 84 × 44? (a) 32000 (b) 3200 (c) 320
  26. 26.Best estimate of 96 × 77? (a) 800 (b) 80000 (c) 8000
  27. 27.Best estimate of 31 × 57? (a) 1800 (b) 180 (c) 18000
  28. 28.Best estimate of 27 × 92? (a) 270 (b) 2700 (c) 27000
  29. 29.Best estimate of 279 + 126? (a) 200 (b) 600 (c) 400
  30. 30.Best estimate of 83 × 26? (a) 24000 (b) 2400 (c) 240
  31. 31.Best estimate of 274 + 603? (a) 900 (b) 700 (c) 1100
  32. 32.Best estimate of 366 + 499? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 66 × 37? (a) 2800 (b) 28000 (c) 280
  34. 34.Best estimate of 841 + 202? (a) 1200 (b) 1000 (c) 800
  35. 35.Best estimate of 488 + 798? (a) 1100 (b) 1300 (c) 1500
  36. 36.Best estimate of 74 × 56? (a) 42000 (b) 420 (c) 4200
  37. 37.Best estimate of 851 + 868? (a) 1600 (b) 2000 (c) 1800
  38. 38.Best estimate of 743 + 151? (a) 900 (b) 1100 (c) 700
  39. 39.Best estimate of 51 × 18? (a) 10000 (b) 100 (c) 1000
  40. 40.Best estimate of 453 + 734? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 1400
  2. 600
  3. 1600
  4. 1000
  5. 1000
  6. 600
  7. 500
  8. 900
  9. 500
  10. 1600
  11. 400
  12. 1500
  13. 500
  14. 700
  15. 500
  16. 2700
  17. 6000
  18. 6300
  19. 2000
  20. 2800
  21. 1600
  22. 1600
  23. 900
  24. 900
  25. 3200
  26. 8000
  27. 1800
  28. 2700
  29. 400
  30. 2400
  31. 900
  32. 900
  33. 2800
  34. 1000
  35. 1300
  36. 4200
  37. 1800
  38. 900
  39. 1000
  40. 1200

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