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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 406 · 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 263 + 579? (a) 1100 (b) 700 (c) 900
  2. 2.Best estimate of 77 × 26? (a) 240 (b) 2400 (c) 24000
  3. 3.Best estimate of 874 + 691? (a) 1800 (b) 1400 (c) 1600
  4. 4.Best estimate of 27 × 42? (a) 12000 (b) 1200 (c) 120
  5. 5.Best estimate of 304 + 282? (a) 600 (b) 400 (c) 800
  6. 6.Best estimate of 772 + 185? (a) 1200 (b) 800 (c) 1000
  7. 7.Best estimate of 671 + 656? (a) 1600 (b) 1200 (c) 1400
  8. 8.Best estimate of 773 + 838? (a) 1800 (b) 1600 (c) 1400
  9. 9.Best estimate of 60 × 34? (a) 1800 (b) 180 (c) 18000
  10. 10.Best estimate of 532 + 351? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 537 + 544? (a) 1200 (b) 1000 (c) 800
  12. 12.Best estimate of 252 + 718? (a) 800 (b) 1000 (c) 1200
  13. 13.Best estimate of 421 + 376? (a) 600 (b) 1000 (c) 800
  14. 14.Best estimate of 56 × 66? (a) 4200 (b) 42000 (c) 420
  15. 15.Best estimate of 251 + 588? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 30 × 29? (a) 900 (b) 90 (c) 9000
  17. 17.Best estimate of 619 + 340? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 351 + 448? (a) 1000 (b) 600 (c) 800
  19. 19.Best estimate of 46 × 77? (a) 4000 (b) 400 (c) 40000
  20. 20.Best estimate of 59 × 52? (a) 3000 (b) 30000 (c) 300
  21. 21.Best estimate of 74 × 47? (a) 350 (b) 35000 (c) 3500
  22. 22.Best estimate of 54 × 21? (a) 100 (b) 10000 (c) 1000
  23. 23.Best estimate of 805 + 860? (a) 1500 (b) 1700 (c) 1900
  24. 24.Best estimate of 73 × 66? (a) 49000 (b) 490 (c) 4900
  25. 25.Best estimate of 39 × 51? (a) 2000 (b) 200 (c) 20000
  26. 26.Best estimate of 62 × 92? (a) 5400 (b) 540 (c) 54000
  27. 27.Best estimate of 199 + 298? (a) 700 (b) 500 (c) 300
  28. 28.Best estimate of 59 × 36? (a) 240 (b) 24000 (c) 2400
  29. 29.Best estimate of 46 × 60? (a) 300 (b) 3000 (c) 30000
  30. 30.Best estimate of 851 + 364? (a) 1500 (b) 1100 (c) 1300
  31. 31.Best estimate of 384 + 447? (a) 1000 (b) 800 (c) 600
  32. 32.Best estimate of 29 × 86? (a) 270 (b) 2700 (c) 27000
  33. 33.Best estimate of 33 × 54? (a) 150 (b) 1500 (c) 15000
  34. 34.Best estimate of 21 × 86? (a) 1800 (b) 180 (c) 18000
  35. 35.Best estimate of 44 × 86? (a) 36000 (b) 360 (c) 3600
  36. 36.Best estimate of 312 + 365? (a) 900 (b) 500 (c) 700
  37. 37.Best estimate of 472 + 723? (a) 1400 (b) 1200 (c) 1000
  38. 38.Best estimate of 184 + 699? (a) 900 (b) 700 (c) 1100
  39. 39.Best estimate of 21 × 26? (a) 6000 (b) 60 (c) 600
  40. 40.Best estimate of 56 × 32? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 900
  2. 2400
  3. 1600
  4. 1200
  5. 600
  6. 1000
  7. 1400
  8. 1600
  9. 1800
  10. 900
  11. 1000
  12. 1000
  13. 800
  14. 4200
  15. 900
  16. 900
  17. 900
  18. 800
  19. 4000
  20. 3000
  21. 3500
  22. 1000
  23. 1700
  24. 4900
  25. 2000
  26. 5400
  27. 500
  28. 2400
  29. 3000
  30. 1300
  31. 800
  32. 2700
  33. 1500
  34. 1800
  35. 3600
  36. 700
  37. 1200
  38. 900
  39. 600
  40. 1800

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