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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 539 · 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 89 × 86? (a) 8100 (b) 81000 (c) 810
  2. 2.Best estimate of 410 + 442? (a) 800 (b) 600 (c) 1000
  3. 3.Best estimate of 12 × 29? (a) 3000 (b) 300 (c) 30
  4. 4.Best estimate of 59 × 50? (a) 3000 (b) 30000 (c) 300
  5. 5.Best estimate of 131 + 421? (a) 700 (b) 500 (c) 300
  6. 6.Best estimate of 736 + 163? (a) 900 (b) 700 (c) 1100
  7. 7.Best estimate of 51 × 74? (a) 35000 (b) 350 (c) 3500
  8. 8.Best estimate of 643 + 542? (a) 1300 (b) 900 (c) 1100
  9. 9.Best estimate of 465 + 202? (a) 500 (b) 700 (c) 900
  10. 10.Best estimate of 44 × 89? (a) 360 (b) 36000 (c) 3600
  11. 11.Best estimate of 68 × 96? (a) 7000 (b) 700 (c) 70000
  12. 12.Best estimate of 71 × 82? (a) 56000 (b) 5600 (c) 560
  13. 13.Best estimate of 68 × 36? (a) 28000 (b) 2800 (c) 280
  14. 14.Best estimate of 532 + 264? (a) 600 (b) 1000 (c) 800
  15. 15.Best estimate of 789 + 406? (a) 1000 (b) 1200 (c) 1400
  16. 16.Best estimate of 410 + 601? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 40 × 27? (a) 12000 (b) 1200 (c) 120
  18. 18.Best estimate of 88 × 78? (a) 72000 (b) 7200 (c) 720
  19. 19.Best estimate of 651 + 683? (a) 1200 (b) 1400 (c) 1600
  20. 20.Best estimate of 673 + 351? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 70 × 22? (a) 140 (b) 1400 (c) 14000
  22. 22.Best estimate of 20 × 44? (a) 8000 (b) 80 (c) 800
  23. 23.Best estimate of 601 + 276? (a) 900 (b) 1100 (c) 700
  24. 24.Best estimate of 636 + 129? (a) 700 (b) 900 (c) 500
  25. 25.Best estimate of 323 + 696? (a) 800 (b) 1000 (c) 1200
  26. 26.Best estimate of 771 + 632? (a) 1200 (b) 1600 (c) 1400
  27. 27.Best estimate of 91 × 66? (a) 630 (b) 6300 (c) 63000
  28. 28.Best estimate of 693 + 825? (a) 1500 (b) 1700 (c) 1300
  29. 29.Best estimate of 765 + 748? (a) 1700 (b) 1300 (c) 1500
  30. 30.Best estimate of 98 × 36? (a) 400 (b) 40000 (c) 4000
  31. 31.Best estimate of 39 × 24? (a) 80 (b) 8000 (c) 800
  32. 32.Best estimate of 23 × 78? (a) 160 (b) 1600 (c) 16000
  33. 33.Best estimate of 723 + 794? (a) 1300 (b) 1500 (c) 1700
  34. 34.Best estimate of 44 × 56? (a) 24000 (b) 240 (c) 2400
  35. 35.Best estimate of 74 × 79? (a) 560 (b) 5600 (c) 56000
  36. 36.Best estimate of 33 × 30? (a) 900 (b) 90 (c) 9000
  37. 37.Best estimate of 293 + 526? (a) 1000 (b) 800 (c) 600
  38. 38.Best estimate of 857 + 211? (a) 900 (b) 1300 (c) 1100
  39. 39.Best estimate of 251 + 280? (a) 400 (b) 600 (c) 800
  40. 40.Best estimate of 171 + 707? (a) 1100 (b) 900 (c) 700

Answer key

  1. 8100
  2. 800
  3. 300
  4. 3000
  5. 500
  6. 900
  7. 3500
  8. 1100
  9. 700
  10. 3600
  11. 7000
  12. 5600
  13. 2800
  14. 800
  15. 1200
  16. 1000
  17. 1200
  18. 7200
  19. 1400
  20. 1100
  21. 1400
  22. 800
  23. 900
  24. 700
  25. 1000
  26. 1400
  27. 6300
  28. 1500
  29. 1500
  30. 4000
  31. 800
  32. 1600
  33. 1500
  34. 2400
  35. 5600
  36. 900
  37. 800
  38. 1100
  39. 600
  40. 900

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