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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 115 · 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 451 + 291? (a) 800 (b) 600 (c) 1000
  2. 2.Best estimate of 16 × 28? (a) 60 (b) 600 (c) 6000
  3. 3.Best estimate of 451 + 863? (a) 1600 (b) 1400 (c) 1200
  4. 4.Best estimate of 523 + 655? (a) 1000 (b) 1200 (c) 1400
  5. 5.Best estimate of 87 × 54? (a) 45000 (b) 450 (c) 4500
  6. 6.Best estimate of 521 + 407? (a) 1100 (b) 900 (c) 700
  7. 7.Best estimate of 96 × 84? (a) 80000 (b) 8000 (c) 800
  8. 8.Best estimate of 739 + 556? (a) 1100 (b) 1300 (c) 1500
  9. 9.Best estimate of 498 + 670? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 23 × 82? (a) 1600 (b) 16000 (c) 160
  11. 11.Best estimate of 370 + 840? (a) 1400 (b) 1000 (c) 1200
  12. 12.Best estimate of 47 × 37? (a) 20000 (b) 2000 (c) 200
  13. 13.Best estimate of 371 + 302? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 28 × 12? (a) 300 (b) 3000 (c) 30
  15. 15.Best estimate of 198 + 690? (a) 900 (b) 1100 (c) 700
  16. 16.Best estimate of 772 + 572? (a) 1600 (b) 1200 (c) 1400
  17. 17.Best estimate of 608 + 444? (a) 1200 (b) 1000 (c) 800
  18. 18.Best estimate of 655 + 245? (a) 1100 (b) 700 (c) 900
  19. 19.Best estimate of 81 × 86? (a) 72000 (b) 7200 (c) 720
  20. 20.Best estimate of 77 × 73? (a) 56000 (b) 560 (c) 5600
  21. 21.Best estimate of 43 × 66? (a) 2800 (b) 280 (c) 28000
  22. 22.Best estimate of 60 × 64? (a) 36000 (b) 360 (c) 3600
  23. 23.Best estimate of 97 × 87? (a) 900 (b) 90000 (c) 9000
  24. 24.Best estimate of 855 + 831? (a) 1500 (b) 1900 (c) 1700
  25. 25.Best estimate of 72 × 63? (a) 420 (b) 42000 (c) 4200
  26. 26.Best estimate of 554 + 445? (a) 1000 (b) 1200 (c) 800
  27. 27.Best estimate of 46 × 66? (a) 3500 (b) 35000 (c) 350
  28. 28.Best estimate of 69 × 62? (a) 420 (b) 42000 (c) 4200
  29. 29.Best estimate of 435 + 667? (a) 900 (b) 1300 (c) 1100
  30. 30.Best estimate of 313 + 577? (a) 1100 (b) 700 (c) 900
  31. 31.Best estimate of 33 × 42? (a) 12000 (b) 120 (c) 1200
  32. 32.Best estimate of 12 × 50? (a) 50 (b) 5000 (c) 500
  33. 33.Best estimate of 96 × 19? (a) 200 (b) 20000 (c) 2000
  34. 34.Best estimate of 148 + 251? (a) 400 (b) 600 (c) 200
  35. 35.Best estimate of 44 × 20? (a) 80 (b) 8000 (c) 800
  36. 36.Best estimate of 32 × 40? (a) 12000 (b) 120 (c) 1200
  37. 37.Best estimate of 22 × 96? (a) 200 (b) 2000 (c) 20000
  38. 38.Best estimate of 787 + 485? (a) 1500 (b) 1100 (c) 1300
  39. 39.Best estimate of 398 + 438? (a) 800 (b) 600 (c) 1000
  40. 40.Best estimate of 519 + 279? (a) 800 (b) 1000 (c) 600

Answer key

  1. 800
  2. 600
  3. 1400
  4. 1200
  5. 4500
  6. 900
  7. 8000
  8. 1300
  9. 1200
  10. 1600
  11. 1200
  12. 2000
  13. 700
  14. 300
  15. 900
  16. 1400
  17. 1000
  18. 900
  19. 7200
  20. 5600
  21. 2800
  22. 3600
  23. 9000
  24. 1700
  25. 4200
  26. 1000
  27. 3500
  28. 4200
  29. 1100
  30. 900
  31. 1200
  32. 500
  33. 2000
  34. 400
  35. 800
  36. 1200
  37. 2000
  38. 1300
  39. 800
  40. 800

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