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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 757 · 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 63 × 47? (a) 300 (b) 3000 (c) 30000
  2. 2.Best estimate of 21 × 28? (a) 6000 (b) 60 (c) 600
  3. 3.Best estimate of 826 + 729? (a) 1300 (b) 1500 (c) 1700
  4. 4.Best estimate of 72 × 18? (a) 140 (b) 1400 (c) 14000
  5. 5.Best estimate of 86 × 20? (a) 180 (b) 1800 (c) 18000
  6. 6.Best estimate of 71 × 84? (a) 56000 (b) 5600 (c) 560
  7. 7.Best estimate of 12 × 79? (a) 8000 (b) 800 (c) 80
  8. 8.Best estimate of 59 × 19? (a) 1200 (b) 120 (c) 12000
  9. 9.Best estimate of 153 + 159? (a) 400 (b) 600 (c) 200
  10. 10.Best estimate of 636 + 651? (a) 1500 (b) 1100 (c) 1300
  11. 11.Best estimate of 406 + 478? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 645 + 138? (a) 900 (b) 500 (c) 700
  13. 13.Best estimate of 847 + 327? (a) 1100 (b) 900 (c) 1300
  14. 14.Best estimate of 77 × 66? (a) 560 (b) 56000 (c) 5600
  15. 15.Best estimate of 708 + 306? (a) 800 (b) 1200 (c) 1000
  16. 16.Best estimate of 652 + 388? (a) 1100 (b) 900 (c) 1300
  17. 17.Best estimate of 27 × 98? (a) 3000 (b) 30000 (c) 300
  18. 18.Best estimate of 248 + 213? (a) 200 (b) 600 (c) 400
  19. 19.Best estimate of 19 × 37? (a) 800 (b) 8000 (c) 80
  20. 20.Best estimate of 324 + 368? (a) 900 (b) 500 (c) 700
  21. 21.Best estimate of 39 × 30? (a) 1200 (b) 12000 (c) 120
  22. 22.Best estimate of 513 + 399? (a) 1100 (b) 700 (c) 900
  23. 23.Best estimate of 51 × 18? (a) 10000 (b) 1000 (c) 100
  24. 24.Best estimate of 679 + 785? (a) 1300 (b) 1700 (c) 1500
  25. 25.Best estimate of 32 × 42? (a) 12000 (b) 1200 (c) 120
  26. 26.Best estimate of 837 + 446? (a) 1400 (b) 1000 (c) 1200
  27. 27.Best estimate of 94 × 81? (a) 7200 (b) 720 (c) 72000
  28. 28.Best estimate of 44 × 84? (a) 3200 (b) 320 (c) 32000
  29. 29.Best estimate of 81 × 47? (a) 4000 (b) 40000 (c) 400
  30. 30.Best estimate of 376 + 751? (a) 1200 (b) 1000 (c) 1400
  31. 31.Best estimate of 377 + 493? (a) 700 (b) 900 (c) 1100
  32. 32.Best estimate of 720 + 660? (a) 1400 (b) 1600 (c) 1200
  33. 33.Best estimate of 323 + 443? (a) 500 (b) 700 (c) 900
  34. 34.Best estimate of 33 × 62? (a) 1800 (b) 180 (c) 18000
  35. 35.Best estimate of 863 + 483? (a) 1200 (b) 1400 (c) 1600
  36. 36.Best estimate of 34 × 40? (a) 120 (b) 12000 (c) 1200
  37. 37.Best estimate of 78 × 88? (a) 720 (b) 72000 (c) 7200
  38. 38.Best estimate of 32 × 12? (a) 3000 (b) 30 (c) 300
  39. 39.Best estimate of 42 × 17? (a) 800 (b) 80 (c) 8000
  40. 40.Best estimate of 254 + 127? (a) 400 (b) 200 (c) 600

Answer key

  1. 3000
  2. 600
  3. 1500
  4. 1400
  5. 1800
  6. 5600
  7. 800
  8. 1200
  9. 400
  10. 1300
  11. 900
  12. 700
  13. 1100
  14. 5600
  15. 1000
  16. 1100
  17. 3000
  18. 400
  19. 800
  20. 700
  21. 1200
  22. 900
  23. 1000
  24. 1500
  25. 1200
  26. 1200
  27. 7200
  28. 3200
  29. 4000
  30. 1200
  31. 900
  32. 1400
  33. 700
  34. 1800
  35. 1400
  36. 1200
  37. 7200
  38. 300
  39. 800
  40. 400

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