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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 651 · 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 541 + 503? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 68 × 41? (a) 2800 (b) 28000 (c) 280
  3. 3.Best estimate of 551 + 393? (a) 800 (b) 1200 (c) 1000
  4. 4.Best estimate of 58 × 36? (a) 2400 (b) 240 (c) 24000
  5. 5.Best estimate of 27 × 53? (a) 15000 (b) 150 (c) 1500
  6. 6.Best estimate of 400 + 775? (a) 1400 (b) 1000 (c) 1200
  7. 7.Best estimate of 82 × 66? (a) 5600 (b) 56000 (c) 560
  8. 8.Best estimate of 16 × 53? (a) 1000 (b) 10000 (c) 100
  9. 9.Best estimate of 40 × 51? (a) 20000 (b) 2000 (c) 200
  10. 10.Best estimate of 64 × 54? (a) 30000 (b) 3000 (c) 300
  11. 11.Best estimate of 61 × 94? (a) 5400 (b) 54000 (c) 540
  12. 12.Best estimate of 61 × 91? (a) 54000 (b) 540 (c) 5400
  13. 13.Best estimate of 866 + 283? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 71 × 91? (a) 6300 (b) 63000 (c) 630
  15. 15.Best estimate of 127 + 416? (a) 500 (b) 300 (c) 700
  16. 16.Best estimate of 752 + 315? (a) 1300 (b) 1100 (c) 900
  17. 17.Best estimate of 688 + 347? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 867 + 744? (a) 1400 (b) 1600 (c) 1800
  19. 19.Best estimate of 818 + 246? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 196 + 189? (a) 400 (b) 600 (c) 200
  21. 21.Best estimate of 72 × 87? (a) 6300 (b) 630 (c) 63000
  22. 22.Best estimate of 42 × 26? (a) 1200 (b) 12000 (c) 120
  23. 23.Best estimate of 93 × 33? (a) 27000 (b) 270 (c) 2700
  24. 24.Best estimate of 335 + 449? (a) 700 (b) 500 (c) 900
  25. 25.Best estimate of 32 × 26? (a) 90 (b) 9000 (c) 900
  26. 26.Best estimate of 23 × 27? (a) 60 (b) 600 (c) 6000
  27. 27.Best estimate of 78 × 12? (a) 80 (b) 8000 (c) 800
  28. 28.Best estimate of 128 + 187? (a) 300 (b) 500 (c) 100
  29. 29.Best estimate of 600 + 612? (a) 1000 (b) 1400 (c) 1200
  30. 30.Best estimate of 27 × 24? (a) 6000 (b) 600 (c) 60
  31. 31.Best estimate of 80 × 44? (a) 32000 (b) 3200 (c) 320
  32. 32.Best estimate of 375 + 587? (a) 1000 (b) 1200 (c) 800
  33. 33.Best estimate of 207 + 226? (a) 600 (b) 200 (c) 400
  34. 34.Best estimate of 93 × 40? (a) 3600 (b) 360 (c) 36000
  35. 35.Best estimate of 197 + 700? (a) 900 (b) 700 (c) 1100
  36. 36.Best estimate of 504 + 215? (a) 700 (b) 900 (c) 500
  37. 37.Best estimate of 33 × 40? (a) 1200 (b) 120 (c) 12000
  38. 38.Best estimate of 22 × 38? (a) 800 (b) 80 (c) 8000
  39. 39.Best estimate of 808 + 748? (a) 1500 (b) 1700 (c) 1300
  40. 40.Best estimate of 567 + 421? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 1000
  2. 2800
  3. 1000
  4. 2400
  5. 1500
  6. 1200
  7. 5600
  8. 1000
  9. 2000
  10. 3000
  11. 5400
  12. 5400
  13. 1200
  14. 6300
  15. 500
  16. 1100
  17. 1000
  18. 1600
  19. 1000
  20. 400
  21. 6300
  22. 1200
  23. 2700
  24. 700
  25. 900
  26. 600
  27. 800
  28. 300
  29. 1200
  30. 600
  31. 3200
  32. 1000
  33. 400
  34. 3600
  35. 900
  36. 700
  37. 1200
  38. 800
  39. 1500
  40. 1000

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