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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 817 · 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 460 + 521? (a) 800 (b) 1200 (c) 1000
  2. 2.Best estimate of 16 × 29? (a) 60 (b) 6000 (c) 600
  3. 3.Best estimate of 96 × 81? (a) 800 (b) 80000 (c) 8000
  4. 4.Best estimate of 37 × 17? (a) 800 (b) 8000 (c) 80
  5. 5.Best estimate of 26 × 20? (a) 6000 (b) 60 (c) 600
  6. 6.Best estimate of 710 + 233? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 554 + 272? (a) 900 (b) 700 (c) 1100
  8. 8.Best estimate of 711 + 247? (a) 900 (b) 1100 (c) 700
  9. 9.Best estimate of 322 + 704? (a) 800 (b) 1000 (c) 1200
  10. 10.Best estimate of 18 × 56? (a) 120 (b) 1200 (c) 12000
  11. 11.Best estimate of 57 × 43? (a) 2400 (b) 24000 (c) 240
  12. 12.Best estimate of 817 + 786? (a) 1800 (b) 1600 (c) 1400
  13. 13.Best estimate of 717 + 499? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 40 × 34? (a) 12000 (b) 1200 (c) 120
  15. 15.Best estimate of 638 + 242? (a) 600 (b) 1000 (c) 800
  16. 16.Best estimate of 804 + 868? (a) 1900 (b) 1500 (c) 1700
  17. 17.Best estimate of 290 + 340? (a) 400 (b) 600 (c) 800
  18. 18.Best estimate of 464 + 415? (a) 1100 (b) 900 (c) 700
  19. 19.Best estimate of 521 + 374? (a) 900 (b) 1100 (c) 700
  20. 20.Best estimate of 820 + 241? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 67 × 83? (a) 560 (b) 5600 (c) 56000
  22. 22.Best estimate of 487 + 408? (a) 1100 (b) 900 (c) 700
  23. 23.Best estimate of 490 + 820? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 66 × 52? (a) 35000 (b) 350 (c) 3500
  25. 25.Best estimate of 83 × 22? (a) 1600 (b) 16000 (c) 160
  26. 26.Best estimate of 16 × 86? (a) 180 (b) 18000 (c) 1800
  27. 27.Best estimate of 22 × 89? (a) 180 (b) 1800 (c) 18000
  28. 28.Best estimate of 408 + 723? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 30 × 26? (a) 90 (b) 900 (c) 9000
  30. 30.Best estimate of 20 × 86? (a) 1800 (b) 18000 (c) 180
  31. 31.Best estimate of 20 × 96? (a) 20000 (b) 200 (c) 2000
  32. 32.Best estimate of 379 + 862? (a) 1500 (b) 1300 (c) 1100
  33. 33.Best estimate of 38 × 21? (a) 80 (b) 800 (c) 8000
  34. 34.Best estimate of 50 × 77? (a) 4000 (b) 400 (c) 40000
  35. 35.Best estimate of 697 + 599? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 693 + 122? (a) 600 (b) 1000 (c) 800
  37. 37.Best estimate of 420 + 805? (a) 1000 (b) 1200 (c) 1400
  38. 38.Best estimate of 91 × 42? (a) 3600 (b) 360 (c) 36000
  39. 39.Best estimate of 286 + 343? (a) 800 (b) 400 (c) 600
  40. 40.Best estimate of 262 + 681? (a) 1000 (b) 1200 (c) 800

Answer key

  1. 1000
  2. 600
  3. 8000
  4. 800
  5. 600
  6. 900
  7. 900
  8. 900
  9. 1000
  10. 1200
  11. 2400
  12. 1600
  13. 1200
  14. 1200
  15. 800
  16. 1700
  17. 600
  18. 900
  19. 900
  20. 1000
  21. 5600
  22. 900
  23. 1300
  24. 3500
  25. 1600
  26. 1800
  27. 1800
  28. 1100
  29. 900
  30. 1800
  31. 2000
  32. 1300
  33. 800
  34. 4000
  35. 1300
  36. 800
  37. 1200
  38. 3600
  39. 600
  40. 1000

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