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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 174 · 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 857 + 141? (a) 1000 (b) 800 (c) 1200
  2. 2.Best estimate of 70 × 51? (a) 350 (b) 3500 (c) 35000
  3. 3.Best estimate of 348 + 489? (a) 800 (b) 1000 (c) 600
  4. 4.Best estimate of 31 × 27? (a) 90 (b) 9000 (c) 900
  5. 5.Best estimate of 674 + 828? (a) 1300 (b) 1700 (c) 1500
  6. 6.Best estimate of 128 + 566? (a) 900 (b) 700 (c) 500
  7. 7.Best estimate of 507 + 506? (a) 1200 (b) 1000 (c) 800
  8. 8.Best estimate of 425 + 769? (a) 1200 (b) 1400 (c) 1000
  9. 9.Best estimate of 352 + 765? (a) 1400 (b) 1200 (c) 1000
  10. 10.Best estimate of 84 × 18? (a) 160 (b) 16000 (c) 1600
  11. 11.Best estimate of 36 × 32? (a) 12000 (b) 120 (c) 1200
  12. 12.Best estimate of 446 + 406? (a) 600 (b) 800 (c) 1000
  13. 13.Best estimate of 841 + 295? (a) 1300 (b) 1100 (c) 900
  14. 14.Best estimate of 79 × 82? (a) 64000 (b) 640 (c) 6400
  15. 15.Best estimate of 645 + 825? (a) 1200 (b) 1600 (c) 1400
  16. 16.Best estimate of 36 × 77? (a) 32000 (b) 3200 (c) 320
  17. 17.Best estimate of 76 × 66? (a) 56000 (b) 5600 (c) 560
  18. 18.Best estimate of 792 + 880? (a) 1500 (b) 1900 (c) 1700
  19. 19.Best estimate of 621 + 174? (a) 800 (b) 1000 (c) 600
  20. 20.Best estimate of 410 + 606? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 18 × 30? (a) 600 (b) 60 (c) 6000
  22. 22.Best estimate of 67 × 17? (a) 14000 (b) 140 (c) 1400
  23. 23.Best estimate of 294 + 251? (a) 800 (b) 600 (c) 400
  24. 24.Best estimate of 33 × 26? (a) 900 (b) 90 (c) 9000
  25. 25.Best estimate of 702 + 384? (a) 1100 (b) 1300 (c) 900
  26. 26.Best estimate of 66 × 46? (a) 350 (b) 3500 (c) 35000
  27. 27.Best estimate of 57 × 33? (a) 180 (b) 18000 (c) 1800
  28. 28.Best estimate of 13 × 80? (a) 800 (b) 8000 (c) 80
  29. 29.Best estimate of 96 × 44? (a) 40000 (b) 4000 (c) 400
  30. 30.Best estimate of 56 × 96? (a) 600 (b) 6000 (c) 60000
  31. 31.Best estimate of 30 × 73? (a) 210 (b) 21000 (c) 2100
  32. 32.Best estimate of 74 × 81? (a) 5600 (b) 560 (c) 56000
  33. 33.Best estimate of 47 × 18? (a) 100 (b) 1000 (c) 10000
  34. 34.Best estimate of 86 × 86? (a) 81000 (b) 8100 (c) 810
  35. 35.Best estimate of 175 + 293? (a) 700 (b) 300 (c) 500
  36. 36.Best estimate of 774 + 302? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 396 + 629? (a) 1200 (b) 1000 (c) 800
  38. 38.Best estimate of 815 + 213? (a) 800 (b) 1200 (c) 1000
  39. 39.Best estimate of 93 × 20? (a) 180 (b) 18000 (c) 1800
  40. 40.Best estimate of 27 × 14? (a) 300 (b) 30 (c) 3000

Answer key

  1. 1000
  2. 3500
  3. 800
  4. 900
  5. 1500
  6. 700
  7. 1000
  8. 1200
  9. 1200
  10. 1600
  11. 1200
  12. 800
  13. 1100
  14. 6400
  15. 1400
  16. 3200
  17. 5600
  18. 1700
  19. 800
  20. 1000
  21. 600
  22. 1400
  23. 600
  24. 900
  25. 1100
  26. 3500
  27. 1800
  28. 800
  29. 4000
  30. 6000
  31. 2100
  32. 5600
  33. 1000
  34. 8100
  35. 500
  36. 1100
  37. 1000
  38. 1000
  39. 1800
  40. 300

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