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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 407 · 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 151 + 631? (a) 1000 (b) 800 (c) 600
  2. 2.Best estimate of 29 × 56? (a) 180 (b) 1800 (c) 18000
  3. 3.Best estimate of 718 + 124? (a) 800 (b) 600 (c) 1000
  4. 4.Best estimate of 82 × 92? (a) 7200 (b) 720 (c) 72000
  5. 5.Best estimate of 18 × 34? (a) 6000 (b) 600 (c) 60
  6. 6.Best estimate of 88 × 36? (a) 3600 (b) 360 (c) 36000
  7. 7.Best estimate of 328 + 559? (a) 700 (b) 900 (c) 1100
  8. 8.Best estimate of 400 + 143? (a) 500 (b) 300 (c) 700
  9. 9.Best estimate of 32 × 21? (a) 6000 (b) 600 (c) 60
  10. 10.Best estimate of 19 × 41? (a) 800 (b) 8000 (c) 80
  11. 11.Best estimate of 540 + 870? (a) 1600 (b) 1400 (c) 1200
  12. 12.Best estimate of 747 + 638? (a) 1100 (b) 1500 (c) 1300
  13. 13.Best estimate of 26 × 70? (a) 2100 (b) 21000 (c) 210
  14. 14.Best estimate of 429 + 194? (a) 600 (b) 800 (c) 400
  15. 15.Best estimate of 753 + 181? (a) 1000 (b) 800 (c) 1200
  16. 16.Best estimate of 488 + 763? (a) 1100 (b) 1500 (c) 1300
  17. 17.Best estimate of 17 × 41? (a) 8000 (b) 800 (c) 80
  18. 18.Best estimate of 73 × 59? (a) 4200 (b) 42000 (c) 420
  19. 19.Best estimate of 36 × 51? (a) 2000 (b) 20000 (c) 200
  20. 20.Best estimate of 644 + 231? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 628 + 231? (a) 1000 (b) 800 (c) 600
  22. 22.Best estimate of 20 × 66? (a) 140 (b) 14000 (c) 1400
  23. 23.Best estimate of 184 + 402? (a) 400 (b) 600 (c) 800
  24. 24.Best estimate of 655 + 336? (a) 1000 (b) 1200 (c) 800
  25. 25.Best estimate of 41 × 16? (a) 8000 (b) 80 (c) 800
  26. 26.Best estimate of 879 + 430? (a) 1100 (b) 1300 (c) 1500
  27. 27.Best estimate of 531 + 676? (a) 1400 (b) 1000 (c) 1200
  28. 28.Best estimate of 385 + 861? (a) 1300 (b) 1100 (c) 1500
  29. 29.Best estimate of 162 + 822? (a) 1200 (b) 1000 (c) 800
  30. 30.Best estimate of 60 × 59? (a) 3600 (b) 36000 (c) 360
  31. 31.Best estimate of 535 + 789? (a) 1100 (b) 1500 (c) 1300
  32. 32.Best estimate of 59 × 44? (a) 2400 (b) 240 (c) 24000
  33. 33.Best estimate of 36 × 76? (a) 320 (b) 32000 (c) 3200
  34. 34.Best estimate of 96 × 53? (a) 50000 (b) 500 (c) 5000
  35. 35.Best estimate of 73 × 29? (a) 21000 (b) 2100 (c) 210
  36. 36.Best estimate of 243 + 809? (a) 1000 (b) 1200 (c) 800
  37. 37.Best estimate of 78 × 26? (a) 2400 (b) 240 (c) 24000
  38. 38.Best estimate of 58 × 36? (a) 240 (b) 24000 (c) 2400
  39. 39.Best estimate of 199 + 273? (a) 500 (b) 700 (c) 300
  40. 40.Best estimate of 421 + 871? (a) 1500 (b) 1300 (c) 1100

Answer key

  1. 800
  2. 1800
  3. 800
  4. 7200
  5. 600
  6. 3600
  7. 900
  8. 500
  9. 600
  10. 800
  11. 1400
  12. 1300
  13. 2100
  14. 600
  15. 1000
  16. 1300
  17. 800
  18. 4200
  19. 2000
  20. 800
  21. 800
  22. 1400
  23. 600
  24. 1000
  25. 800
  26. 1300
  27. 1200
  28. 1300
  29. 1000
  30. 3600
  31. 1300
  32. 2400
  33. 3200
  34. 5000
  35. 2100
  36. 1000
  37. 2400
  38. 2400
  39. 500
  40. 1300

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