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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 413 · 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 66 × 64? (a) 42000 (b) 420 (c) 4200
  2. 2.Best estimate of 80 × 94? (a) 720 (b) 7200 (c) 72000
  3. 3.Best estimate of 567 + 366? (a) 1200 (b) 1000 (c) 800
  4. 4.Best estimate of 62 × 70? (a) 4200 (b) 420 (c) 42000
  5. 5.Best estimate of 709 + 186? (a) 900 (b) 700 (c) 1100
  6. 6.Best estimate of 855 + 852? (a) 2000 (b) 1600 (c) 1800
  7. 7.Best estimate of 47 × 64? (a) 30000 (b) 3000 (c) 300
  8. 8.Best estimate of 46 × 24? (a) 10000 (b) 1000 (c) 100
  9. 9.Best estimate of 268 + 862? (a) 1200 (b) 1400 (c) 1000
  10. 10.Best estimate of 91 × 43? (a) 360 (b) 3600 (c) 36000
  11. 11.Best estimate of 21 × 44? (a) 800 (b) 80 (c) 8000
  12. 12.Best estimate of 664 + 209? (a) 700 (b) 900 (c) 1100
  13. 13.Best estimate of 48 × 87? (a) 4500 (b) 450 (c) 45000
  14. 14.Best estimate of 504 + 720? (a) 1200 (b) 1000 (c) 1400
  15. 15.Best estimate of 36 × 82? (a) 320 (b) 3200 (c) 32000
  16. 16.Best estimate of 384 + 472? (a) 900 (b) 700 (c) 1100
  17. 17.Best estimate of 756 + 128? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 376 + 252? (a) 900 (b) 700 (c) 500
  19. 19.Best estimate of 669 + 343? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 86 × 16? (a) 18000 (b) 1800 (c) 180
  21. 21.Best estimate of 18 × 74? (a) 1400 (b) 140 (c) 14000
  22. 22.Best estimate of 17 × 56? (a) 120 (b) 12000 (c) 1200
  23. 23.Best estimate of 694 + 351? (a) 900 (b) 1100 (c) 1300
  24. 24.Best estimate of 718 + 184? (a) 1100 (b) 900 (c) 700
  25. 25.Best estimate of 358 + 803? (a) 1400 (b) 1000 (c) 1200
  26. 26.Best estimate of 181 + 588? (a) 600 (b) 1000 (c) 800
  27. 27.Best estimate of 482 + 502? (a) 1200 (b) 1000 (c) 800
  28. 28.Best estimate of 77 × 20? (a) 1600 (b) 160 (c) 16000
  29. 29.Best estimate of 602 + 157? (a) 600 (b) 800 (c) 1000
  30. 30.Best estimate of 82 × 37? (a) 320 (b) 3200 (c) 32000
  31. 31.Best estimate of 92 × 61? (a) 5400 (b) 540 (c) 54000
  32. 32.Best estimate of 733 + 374? (a) 900 (b) 1100 (c) 1300
  33. 33.Best estimate of 76 × 12? (a) 8000 (b) 800 (c) 80
  34. 34.Best estimate of 96 × 83? (a) 8000 (b) 800 (c) 80000
  35. 35.Best estimate of 86 × 64? (a) 5400 (b) 540 (c) 54000
  36. 36.Best estimate of 399 + 188? (a) 600 (b) 800 (c) 400
  37. 37.Best estimate of 33 × 41? (a) 12000 (b) 1200 (c) 120
  38. 38.Best estimate of 296 + 373? (a) 900 (b) 500 (c) 700
  39. 39.Best estimate of 142 + 760? (a) 900 (b) 700 (c) 1100
  40. 40.Best estimate of 623 + 384? (a) 1000 (b) 1200 (c) 800

Answer key

  1. 4200
  2. 7200
  3. 1000
  4. 4200
  5. 900
  6. 1800
  7. 3000
  8. 1000
  9. 1200
  10. 3600
  11. 800
  12. 900
  13. 4500
  14. 1200
  15. 3200
  16. 900
  17. 900
  18. 700
  19. 1000
  20. 1800
  21. 1400
  22. 1200
  23. 1100
  24. 900
  25. 1200
  26. 800
  27. 1000
  28. 1600
  29. 800
  30. 3200
  31. 5400
  32. 1100
  33. 800
  34. 8000
  35. 5400
  36. 600
  37. 1200
  38. 700
  39. 900
  40. 1000

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