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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 478 · 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 665 + 377? (a) 1300 (b) 1100 (c) 900
  2. 2.Best estimate of 805 + 645? (a) 1600 (b) 1400 (c) 1200
  3. 3.Best estimate of 36 × 32? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 49 × 16? (a) 10000 (b) 1000 (c) 100
  5. 5.Best estimate of 59 × 12? (a) 6000 (b) 60 (c) 600
  6. 6.Best estimate of 497 + 369? (a) 1100 (b) 700 (c) 900
  7. 7.Best estimate of 363 + 781? (a) 1200 (b) 1400 (c) 1000
  8. 8.Best estimate of 205 + 476? (a) 900 (b) 700 (c) 500
  9. 9.Best estimate of 413 + 146? (a) 700 (b) 300 (c) 500
  10. 10.Best estimate of 31 × 20? (a) 6000 (b) 60 (c) 600
  11. 11.Best estimate of 47 × 54? (a) 2500 (b) 250 (c) 25000
  12. 12.Best estimate of 36 × 94? (a) 36000 (b) 3600 (c) 360
  13. 13.Best estimate of 21 × 59? (a) 12000 (b) 1200 (c) 120
  14. 14.Best estimate of 828 + 339? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 14 × 12? (a) 100 (b) 10 (c) 1000
  16. 16.Best estimate of 585 + 344? (a) 700 (b) 900 (c) 1100
  17. 17.Best estimate of 81 × 53? (a) 40000 (b) 4000 (c) 400
  18. 18.Best estimate of 36 × 98? (a) 4000 (b) 400 (c) 40000
  19. 19.Best estimate of 860 + 778? (a) 1900 (b) 1500 (c) 1700
  20. 20.Best estimate of 842 + 556? (a) 1400 (b) 1600 (c) 1200
  21. 21.Best estimate of 89 × 62? (a) 540 (b) 5400 (c) 54000
  22. 22.Best estimate of 16 × 38? (a) 8000 (b) 800 (c) 80
  23. 23.Best estimate of 19 × 58? (a) 12000 (b) 1200 (c) 120
  24. 24.Best estimate of 26 × 54? (a) 1500 (b) 150 (c) 15000
  25. 25.Best estimate of 387 + 173? (a) 600 (b) 400 (c) 800
  26. 26.Best estimate of 309 + 569? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 42 × 89? (a) 360 (b) 36000 (c) 3600
  28. 28.Best estimate of 69 × 49? (a) 3500 (b) 35000 (c) 350
  29. 29.Best estimate of 184 + 194? (a) 600 (b) 400 (c) 200
  30. 30.Best estimate of 66 × 66? (a) 490 (b) 49000 (c) 4900
  31. 31.Best estimate of 96 × 73? (a) 70000 (b) 700 (c) 7000
  32. 32.Best estimate of 365 + 846? (a) 1400 (b) 1200 (c) 1000
  33. 33.Best estimate of 16 × 44? (a) 800 (b) 8000 (c) 80
  34. 34.Best estimate of 582 + 594? (a) 1000 (b) 1200 (c) 1400
  35. 35.Best estimate of 372 + 134? (a) 500 (b) 300 (c) 700
  36. 36.Best estimate of 66 × 63? (a) 4200 (b) 42000 (c) 420
  37. 37.Best estimate of 49 × 39? (a) 20000 (b) 200 (c) 2000
  38. 38.Best estimate of 329 + 324? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 49 × 80? (a) 400 (b) 4000 (c) 40000
  40. 40.Best estimate of 58 × 48? (a) 3000 (b) 300 (c) 30000

Answer key

  1. 1100
  2. 1400
  3. 1200
  4. 1000
  5. 600
  6. 900
  7. 1200
  8. 700
  9. 500
  10. 600
  11. 2500
  12. 3600
  13. 1200
  14. 1100
  15. 100
  16. 900
  17. 4000
  18. 4000
  19. 1700
  20. 1400
  21. 5400
  22. 800
  23. 1200
  24. 1500
  25. 600
  26. 900
  27. 3600
  28. 3500
  29. 400
  30. 4900
  31. 7000
  32. 1200
  33. 800
  34. 1200
  35. 500
  36. 4200
  37. 2000
  38. 600
  39. 4000
  40. 3000

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