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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 110 · 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 96 × 16? (a) 2000 (b) 20000 (c) 200
  2. 2.Best estimate of 20 × 16? (a) 4000 (b) 40 (c) 400
  3. 3.Best estimate of 608 + 853? (a) 1500 (b) 1300 (c) 1700
  4. 4.Best estimate of 719 + 825? (a) 1500 (b) 1700 (c) 1300
  5. 5.Best estimate of 43 × 61? (a) 2400 (b) 24000 (c) 240
  6. 6.Best estimate of 91 × 59? (a) 54000 (b) 5400 (c) 540
  7. 7.Best estimate of 96 × 43? (a) 4000 (b) 40000 (c) 400
  8. 8.Best estimate of 70 × 57? (a) 420 (b) 4200 (c) 42000
  9. 9.Best estimate of 391 + 139? (a) 700 (b) 500 (c) 300
  10. 10.Best estimate of 479 + 747? (a) 1000 (b) 1200 (c) 1400
  11. 11.Best estimate of 14 × 50? (a) 50 (b) 500 (c) 5000
  12. 12.Best estimate of 63 × 49? (a) 300 (b) 30000 (c) 3000
  13. 13.Best estimate of 833 + 789? (a) 1400 (b) 1800 (c) 1600
  14. 14.Best estimate of 37 × 16? (a) 800 (b) 80 (c) 8000
  15. 15.Best estimate of 508 + 593? (a) 900 (b) 1300 (c) 1100
  16. 16.Best estimate of 231 + 474? (a) 700 (b) 900 (c) 500
  17. 17.Best estimate of 47 × 56? (a) 3000 (b) 30000 (c) 300
  18. 18.Best estimate of 84 × 93? (a) 72000 (b) 7200 (c) 720
  19. 19.Best estimate of 40 × 66? (a) 280 (b) 2800 (c) 28000
  20. 20.Best estimate of 677 + 198? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 13 × 86? (a) 90 (b) 900 (c) 9000
  22. 22.Best estimate of 37 × 17? (a) 800 (b) 80 (c) 8000
  23. 23.Best estimate of 781 + 868? (a) 1500 (b) 1700 (c) 1900
  24. 24.Best estimate of 805 + 418? (a) 1200 (b) 1400 (c) 1000
  25. 25.Best estimate of 21 × 84? (a) 16000 (b) 1600 (c) 160
  26. 26.Best estimate of 82 × 68? (a) 560 (b) 5600 (c) 56000
  27. 27.Best estimate of 240 + 226? (a) 400 (b) 200 (c) 600
  28. 28.Best estimate of 40 × 63? (a) 2400 (b) 240 (c) 24000
  29. 29.Best estimate of 217 + 608? (a) 1000 (b) 600 (c) 800
  30. 30.Best estimate of 125 + 159? (a) 300 (b) 100 (c) 500
  31. 31.Best estimate of 81 × 63? (a) 480 (b) 4800 (c) 48000
  32. 32.Best estimate of 539 + 468? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 804 + 856? (a) 1500 (b) 1700 (c) 1900
  34. 34.Best estimate of 17 × 86? (a) 18000 (b) 1800 (c) 180
  35. 35.Best estimate of 827 + 178? (a) 1000 (b) 800 (c) 1200
  36. 36.Best estimate of 303 + 530? (a) 800 (b) 1000 (c) 600
  37. 37.Best estimate of 355 + 189? (a) 800 (b) 600 (c) 400
  38. 38.Best estimate of 730 + 253? (a) 800 (b) 1000 (c) 1200
  39. 39.Best estimate of 67 × 29? (a) 21000 (b) 210 (c) 2100
  40. 40.Best estimate of 405 + 143? (a) 700 (b) 300 (c) 500

Answer key

  1. 2000
  2. 400
  3. 1500
  4. 1500
  5. 2400
  6. 5400
  7. 4000
  8. 4200
  9. 500
  10. 1200
  11. 500
  12. 3000
  13. 1600
  14. 800
  15. 1100
  16. 700
  17. 3000
  18. 7200
  19. 2800
  20. 900
  21. 900
  22. 800
  23. 1700
  24. 1200
  25. 1600
  26. 5600
  27. 400
  28. 2400
  29. 800
  30. 300
  31. 4800
  32. 1000
  33. 1700
  34. 1800
  35. 1000
  36. 800
  37. 600
  38. 1000
  39. 2100
  40. 500

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