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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 12 · 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 252 + 692? (a) 800 (b) 1200 (c) 1000
  2. 2.Best estimate of 751 + 648? (a) 1200 (b) 1400 (c) 1600
  3. 3.Best estimate of 844 + 335? (a) 1300 (b) 1100 (c) 900
  4. 4.Best estimate of 869 + 513? (a) 1600 (b) 1200 (c) 1400
  5. 5.Best estimate of 225 + 699? (a) 1100 (b) 900 (c) 700
  6. 6.Best estimate of 147 + 735? (a) 800 (b) 1000 (c) 600
  7. 7.Best estimate of 77 × 83? (a) 64000 (b) 6400 (c) 640
  8. 8.Best estimate of 296 + 699? (a) 1000 (b) 1200 (c) 800
  9. 9.Best estimate of 60 × 91? (a) 54000 (b) 540 (c) 5400
  10. 10.Best estimate of 159 + 802? (a) 1000 (b) 1200 (c) 800
  11. 11.Best estimate of 452 + 861? (a) 1200 (b) 1600 (c) 1400
  12. 12.Best estimate of 224 + 608? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 26 × 37? (a) 12000 (b) 1200 (c) 120
  14. 14.Best estimate of 803 + 126? (a) 700 (b) 1100 (c) 900
  15. 15.Best estimate of 38 × 17? (a) 80 (b) 8000 (c) 800
  16. 16.Best estimate of 874 + 588? (a) 1300 (b) 1700 (c) 1500
  17. 17.Best estimate of 237 + 132? (a) 500 (b) 100 (c) 300
  18. 18.Best estimate of 30 × 90? (a) 27000 (b) 2700 (c) 270
  19. 19.Best estimate of 16 × 14? (a) 20 (b) 200 (c) 2000
  20. 20.Best estimate of 474 + 196? (a) 500 (b) 900 (c) 700
  21. 21.Best estimate of 47 × 21? (a) 10000 (b) 100 (c) 1000
  22. 22.Best estimate of 409 + 223? (a) 400 (b) 600 (c) 800
  23. 23.Best estimate of 96 × 72? (a) 700 (b) 7000 (c) 70000
  24. 24.Best estimate of 86 × 66? (a) 63000 (b) 6300 (c) 630
  25. 25.Best estimate of 86 × 12? (a) 9000 (b) 900 (c) 90
  26. 26.Best estimate of 146 + 153? (a) 300 (b) 100 (c) 500
  27. 27.Best estimate of 93 × 28? (a) 270 (b) 27000 (c) 2700
  28. 28.Best estimate of 793 + 569? (a) 1400 (b) 1600 (c) 1200
  29. 29.Best estimate of 40 × 94? (a) 360 (b) 3600 (c) 36000
  30. 30.Best estimate of 89 × 28? (a) 2700 (b) 270 (c) 27000
  31. 31.Best estimate of 58 × 26? (a) 1800 (b) 180 (c) 18000
  32. 32.Best estimate of 50 × 16? (a) 10000 (b) 100 (c) 1000
  33. 33.Best estimate of 640 + 819? (a) 1400 (b) 1200 (c) 1600
  34. 34.Best estimate of 661 + 494? (a) 1400 (b) 1200 (c) 1000
  35. 35.Best estimate of 876 + 151? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 18 × 33? (a) 600 (b) 6000 (c) 60
  37. 37.Best estimate of 582 + 207? (a) 1000 (b) 800 (c) 600
  38. 38.Best estimate of 69 × 18? (a) 1400 (b) 14000 (c) 140
  39. 39.Best estimate of 673 + 258? (a) 1000 (b) 1200 (c) 800
  40. 40.Best estimate of 753 + 758? (a) 1400 (b) 1600 (c) 1800

Answer key

  1. 1000
  2. 1400
  3. 1100
  4. 1400
  5. 900
  6. 800
  7. 6400
  8. 1000
  9. 5400
  10. 1000
  11. 1400
  12. 800
  13. 1200
  14. 900
  15. 800
  16. 1500
  17. 300
  18. 2700
  19. 200
  20. 700
  21. 1000
  22. 600
  23. 7000
  24. 6300
  25. 900
  26. 300
  27. 2700
  28. 1400
  29. 3600
  30. 2700
  31. 1800
  32. 1000
  33. 1400
  34. 1200
  35. 1100
  36. 600
  37. 800
  38. 1400
  39. 1000
  40. 1600

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