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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 435 · 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 48 × 16? (a) 100 (b) 10000 (c) 1000
  2. 2.Best estimate of 749 + 291? (a) 1000 (b) 1200 (c) 800
  3. 3.Best estimate of 51 × 18? (a) 1000 (b) 10000 (c) 100
  4. 4.Best estimate of 49 × 68? (a) 35000 (b) 350 (c) 3500
  5. 5.Best estimate of 93 × 78? (a) 72000 (b) 7200 (c) 720
  6. 6.Best estimate of 34 × 52? (a) 150 (b) 1500 (c) 15000
  7. 7.Best estimate of 425 + 614? (a) 1200 (b) 800 (c) 1000
  8. 8.Best estimate of 619 + 230? (a) 800 (b) 1000 (c) 600
  9. 9.Best estimate of 81 × 12? (a) 80 (b) 800 (c) 8000
  10. 10.Best estimate of 37 × 79? (a) 320 (b) 32000 (c) 3200
  11. 11.Best estimate of 40 × 16? (a) 800 (b) 80 (c) 8000
  12. 12.Best estimate of 94 × 49? (a) 45000 (b) 450 (c) 4500
  13. 13.Best estimate of 48 × 62? (a) 3000 (b) 30000 (c) 300
  14. 14.Best estimate of 39 × 61? (a) 24000 (b) 240 (c) 2400
  15. 15.Best estimate of 385 + 213? (a) 800 (b) 400 (c) 600
  16. 16.Best estimate of 42 × 46? (a) 2000 (b) 20000 (c) 200
  17. 17.Best estimate of 96 × 56? (a) 60000 (b) 600 (c) 6000
  18. 18.Best estimate of 708 + 133? (a) 800 (b) 600 (c) 1000
  19. 19.Best estimate of 733 + 691? (a) 1400 (b) 1200 (c) 1600
  20. 20.Best estimate of 29 × 34? (a) 900 (b) 90 (c) 9000
  21. 21.Best estimate of 798 + 413? (a) 1000 (b) 1200 (c) 1400
  22. 22.Best estimate of 442 + 144? (a) 700 (b) 500 (c) 300
  23. 23.Best estimate of 22 × 38? (a) 800 (b) 80 (c) 8000
  24. 24.Best estimate of 134 + 527? (a) 400 (b) 600 (c) 800
  25. 25.Best estimate of 546 + 566? (a) 1100 (b) 1300 (c) 900
  26. 26.Best estimate of 14 × 28? (a) 300 (b) 3000 (c) 30
  27. 27.Best estimate of 867 + 302? (a) 1200 (b) 1000 (c) 1400
  28. 28.Best estimate of 207 + 424? (a) 600 (b) 800 (c) 400
  29. 29.Best estimate of 76 × 42? (a) 3200 (b) 32000 (c) 320
  30. 30.Best estimate of 76 × 66? (a) 560 (b) 5600 (c) 56000
  31. 31.Best estimate of 609 + 522? (a) 1300 (b) 900 (c) 1100
  32. 32.Best estimate of 31 × 16? (a) 6000 (b) 600 (c) 60
  33. 33.Best estimate of 27 × 17? (a) 6000 (b) 600 (c) 60
  34. 34.Best estimate of 756 + 568? (a) 1600 (b) 1400 (c) 1200
  35. 35.Best estimate of 33 × 20? (a) 60 (b) 600 (c) 6000
  36. 36.Best estimate of 426 + 741? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 94 × 39? (a) 3600 (b) 360 (c) 36000
  38. 38.Best estimate of 16 × 41? (a) 800 (b) 8000 (c) 80
  39. 39.Best estimate of 81 × 36? (a) 32000 (b) 3200 (c) 320
  40. 40.Best estimate of 58 × 28? (a) 18000 (b) 180 (c) 1800

Answer key

  1. 1000
  2. 1000
  3. 1000
  4. 3500
  5. 7200
  6. 1500
  7. 1000
  8. 800
  9. 800
  10. 3200
  11. 800
  12. 4500
  13. 3000
  14. 2400
  15. 600
  16. 2000
  17. 6000
  18. 800
  19. 1400
  20. 900
  21. 1200
  22. 500
  23. 800
  24. 600
  25. 1100
  26. 300
  27. 1200
  28. 600
  29. 3200
  30. 5600
  31. 1100
  32. 600
  33. 600
  34. 1400
  35. 600
  36. 1100
  37. 3600
  38. 800
  39. 3200
  40. 1800

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