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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 55 · 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 29 × 44? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 310 + 855? (a) 1200 (b) 1000 (c) 1400
  3. 3.Best estimate of 42 × 26? (a) 12000 (b) 1200 (c) 120
  4. 4.Best estimate of 73 × 57? (a) 420 (b) 4200 (c) 42000
  5. 5.Best estimate of 63 × 26? (a) 18000 (b) 180 (c) 1800
  6. 6.Best estimate of 217 + 129? (a) 100 (b) 500 (c) 300
  7. 7.Best estimate of 760 + 290? (a) 1100 (b) 900 (c) 1300
  8. 8.Best estimate of 80 × 98? (a) 8000 (b) 800 (c) 80000
  9. 9.Best estimate of 51 × 20? (a) 1000 (b) 100 (c) 10000
  10. 10.Best estimate of 14 × 56? (a) 6000 (b) 600 (c) 60
  11. 11.Best estimate of 29 × 59? (a) 1800 (b) 180 (c) 18000
  12. 12.Best estimate of 73 × 24? (a) 1400 (b) 14000 (c) 140
  13. 13.Best estimate of 61 × 16? (a) 1200 (b) 120 (c) 12000
  14. 14.Best estimate of 369 + 606? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 593 + 567? (a) 1200 (b) 1000 (c) 1400
  16. 16.Best estimate of 88 × 58? (a) 5400 (b) 540 (c) 54000
  17. 17.Best estimate of 423 + 316? (a) 900 (b) 500 (c) 700
  18. 18.Best estimate of 306 + 232? (a) 300 (b) 700 (c) 500
  19. 19.Best estimate of 52 × 22? (a) 1000 (b) 10000 (c) 100
  20. 20.Best estimate of 32 × 41? (a) 120 (b) 1200 (c) 12000
  21. 21.Best estimate of 46 × 18? (a) 10000 (b) 100 (c) 1000
  22. 22.Best estimate of 407 + 412? (a) 800 (b) 1000 (c) 600
  23. 23.Best estimate of 872 + 331? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 23 × 22? (a) 400 (b) 4000 (c) 40
  25. 25.Best estimate of 96 × 12? (a) 10000 (b) 100 (c) 1000
  26. 26.Best estimate of 479 + 338? (a) 1000 (b) 600 (c) 800
  27. 27.Best estimate of 223 + 798? (a) 1200 (b) 1000 (c) 800
  28. 28.Best estimate of 59 × 57? (a) 3600 (b) 360 (c) 36000
  29. 29.Best estimate of 375 + 363? (a) 1000 (b) 600 (c) 800
  30. 30.Best estimate of 74 × 82? (a) 5600 (b) 560 (c) 56000
  31. 31.Best estimate of 141 + 807? (a) 900 (b) 700 (c) 1100
  32. 32.Best estimate of 51 × 63? (a) 300 (b) 30000 (c) 3000
  33. 33.Best estimate of 26 × 36? (a) 12000 (b) 120 (c) 1200
  34. 34.Best estimate of 21 × 16? (a) 400 (b) 40 (c) 4000
  35. 35.Best estimate of 48 × 43? (a) 2000 (b) 20000 (c) 200
  36. 36.Best estimate of 297 + 708? (a) 1000 (b) 1200 (c) 800
  37. 37.Best estimate of 64 × 18? (a) 12000 (b) 1200 (c) 120
  38. 38.Best estimate of 53 × 66? (a) 3500 (b) 350 (c) 35000
  39. 39.Best estimate of 66 × 93? (a) 63000 (b) 6300 (c) 630
  40. 40.Best estimate of 362 + 707? (a) 1100 (b) 1300 (c) 900

Answer key

  1. 1200
  2. 1200
  3. 1200
  4. 4200
  5. 1800
  6. 300
  7. 1100
  8. 8000
  9. 1000
  10. 600
  11. 1800
  12. 1400
  13. 1200
  14. 1000
  15. 1200
  16. 5400
  17. 700
  18. 500
  19. 1000
  20. 1200
  21. 1000
  22. 800
  23. 1200
  24. 400
  25. 1000
  26. 800
  27. 1000
  28. 3600
  29. 800
  30. 5600
  31. 900
  32. 3000
  33. 1200
  34. 400
  35. 2000
  36. 1000
  37. 1200
  38. 3500
  39. 6300
  40. 1100

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