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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 821 · 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 69 × 60? (a) 420 (b) 4200 (c) 42000
  2. 2.Best estimate of 438 + 363? (a) 1000 (b) 600 (c) 800
  3. 3.Best estimate of 404 + 261? (a) 900 (b) 700 (c) 500
  4. 4.Best estimate of 16 × 81? (a) 16000 (b) 160 (c) 1600
  5. 5.Best estimate of 40 × 60? (a) 2400 (b) 24000 (c) 240
  6. 6.Best estimate of 53 × 37? (a) 200 (b) 20000 (c) 2000
  7. 7.Best estimate of 704 + 556? (a) 1300 (b) 1500 (c) 1100
  8. 8.Best estimate of 36 × 58? (a) 24000 (b) 240 (c) 2400
  9. 9.Best estimate of 18 × 46? (a) 1000 (b) 100 (c) 10000
  10. 10.Best estimate of 64 × 63? (a) 3600 (b) 360 (c) 36000
  11. 11.Best estimate of 871 + 605? (a) 1700 (b) 1300 (c) 1500
  12. 12.Best estimate of 62 × 86? (a) 540 (b) 5400 (c) 54000
  13. 13.Best estimate of 544 + 457? (a) 1000 (b) 800 (c) 1200
  14. 14.Best estimate of 445 + 863? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 810 + 397? (a) 1200 (b) 1400 (c) 1000
  16. 16.Best estimate of 444 + 211? (a) 600 (b) 400 (c) 800
  17. 17.Best estimate of 515 + 218? (a) 700 (b) 500 (c) 900
  18. 18.Best estimate of 63 × 32? (a) 180 (b) 18000 (c) 1800
  19. 19.Best estimate of 56 × 89? (a) 54000 (b) 540 (c) 5400
  20. 20.Best estimate of 31 × 76? (a) 24000 (b) 240 (c) 2400
  21. 21.Best estimate of 94 × 84? (a) 7200 (b) 72000 (c) 720
  22. 22.Best estimate of 791 + 682? (a) 1700 (b) 1500 (c) 1300
  23. 23.Best estimate of 80 × 31? (a) 2400 (b) 24000 (c) 240
  24. 24.Best estimate of 133 + 590? (a) 500 (b) 900 (c) 700
  25. 25.Best estimate of 522 + 363? (a) 900 (b) 1100 (c) 700
  26. 26.Best estimate of 600 + 480? (a) 1100 (b) 1300 (c) 900
  27. 27.Best estimate of 670 + 529? (a) 1000 (b) 1400 (c) 1200
  28. 28.Best estimate of 70 × 66? (a) 490 (b) 49000 (c) 4900
  29. 29.Best estimate of 37 × 21? (a) 8000 (b) 80 (c) 800
  30. 30.Best estimate of 204 + 552? (a) 1000 (b) 600 (c) 800
  31. 31.Best estimate of 28 × 67? (a) 2100 (b) 21000 (c) 210
  32. 32.Best estimate of 58 × 96? (a) 6000 (b) 60000 (c) 600
  33. 33.Best estimate of 71 × 44? (a) 28000 (b) 2800 (c) 280
  34. 34.Best estimate of 47 × 39? (a) 2000 (b) 200 (c) 20000
  35. 35.Best estimate of 227 + 317? (a) 700 (b) 500 (c) 300
  36. 36.Best estimate of 40 × 66? (a) 28000 (b) 2800 (c) 280
  37. 37.Best estimate of 33 × 74? (a) 21000 (b) 2100 (c) 210
  38. 38.Best estimate of 344 + 320? (a) 600 (b) 400 (c) 800
  39. 39.Best estimate of 397 + 147? (a) 700 (b) 300 (c) 500
  40. 40.Best estimate of 432 + 742? (a) 1100 (b) 900 (c) 1300

Answer key

  1. 4200
  2. 800
  3. 700
  4. 1600
  5. 2400
  6. 2000
  7. 1300
  8. 2400
  9. 1000
  10. 3600
  11. 1500
  12. 5400
  13. 1000
  14. 1300
  15. 1200
  16. 600
  17. 700
  18. 1800
  19. 5400
  20. 2400
  21. 7200
  22. 1500
  23. 2400
  24. 700
  25. 900
  26. 1100
  27. 1200
  28. 4900
  29. 800
  30. 800
  31. 2100
  32. 6000
  33. 2800
  34. 2000
  35. 500
  36. 2800
  37. 2100
  38. 600
  39. 500
  40. 1100

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