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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 700 · 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 17 × 90? (a) 18000 (b) 180 (c) 1800
  2. 2.Best estimate of 77 × 46? (a) 400 (b) 4000 (c) 40000
  3. 3.Best estimate of 16 × 28? (a) 6000 (b) 600 (c) 60
  4. 4.Best estimate of 715 + 256? (a) 1200 (b) 800 (c) 1000
  5. 5.Best estimate of 77 × 26? (a) 240 (b) 2400 (c) 24000
  6. 6.Best estimate of 772 + 328? (a) 900 (b) 1300 (c) 1100
  7. 7.Best estimate of 865 + 802? (a) 1500 (b) 1900 (c) 1700
  8. 8.Best estimate of 857 + 213? (a) 1100 (b) 900 (c) 1300
  9. 9.Best estimate of 621 + 191? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 475 + 179? (a) 500 (b) 700 (c) 900
  11. 11.Best estimate of 60 × 93? (a) 540 (b) 54000 (c) 5400
  12. 12.Best estimate of 506 + 591? (a) 1300 (b) 900 (c) 1100
  13. 13.Best estimate of 251 + 717? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 762 + 441? (a) 1200 (b) 1400 (c) 1000
  15. 15.Best estimate of 70 × 68? (a) 49000 (b) 490 (c) 4900
  16. 16.Best estimate of 818 + 221? (a) 1000 (b) 800 (c) 1200
  17. 17.Best estimate of 265 + 378? (a) 900 (b) 500 (c) 700
  18. 18.Best estimate of 303 + 420? (a) 900 (b) 500 (c) 700
  19. 19.Best estimate of 51 × 71? (a) 35000 (b) 350 (c) 3500
  20. 20.Best estimate of 87 × 36? (a) 36000 (b) 3600 (c) 360
  21. 21.Best estimate of 642 + 458? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 643 + 289? (a) 700 (b) 1100 (c) 900
  23. 23.Best estimate of 548 + 259? (a) 600 (b) 800 (c) 1000
  24. 24.Best estimate of 47 × 77? (a) 400 (b) 40000 (c) 4000
  25. 25.Best estimate of 44 × 32? (a) 1200 (b) 12000 (c) 120
  26. 26.Best estimate of 63 × 72? (a) 42000 (b) 4200 (c) 420
  27. 27.Best estimate of 297 + 257? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 788 + 359? (a) 1400 (b) 1200 (c) 1000
  29. 29.Best estimate of 96 × 29? (a) 3000 (b) 30000 (c) 300
  30. 30.Best estimate of 61 × 24? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 43 × 53? (a) 20000 (b) 2000 (c) 200
  32. 32.Best estimate of 97 × 86? (a) 900 (b) 90000 (c) 9000
  33. 33.Best estimate of 458 + 158? (a) 900 (b) 500 (c) 700
  34. 34.Best estimate of 495 + 702? (a) 1200 (b) 1400 (c) 1000
  35. 35.Best estimate of 92 × 66? (a) 6300 (b) 63000 (c) 630
  36. 36.Best estimate of 69 × 41? (a) 2800 (b) 28000 (c) 280
  37. 37.Best estimate of 281 + 706? (a) 1200 (b) 800 (c) 1000
  38. 38.Best estimate of 627 + 164? (a) 600 (b) 800 (c) 1000
  39. 39.Best estimate of 72 × 16? (a) 1400 (b) 14000 (c) 140
  40. 40.Best estimate of 33 × 29? (a) 9000 (b) 900 (c) 90

Answer key

  1. 1800
  2. 4000
  3. 600
  4. 1000
  5. 2400
  6. 1100
  7. 1700
  8. 1100
  9. 800
  10. 700
  11. 5400
  12. 1100
  13. 1000
  14. 1200
  15. 4900
  16. 1000
  17. 700
  18. 700
  19. 3500
  20. 3600
  21. 1100
  22. 900
  23. 800
  24. 4000
  25. 1200
  26. 4200
  27. 600
  28. 1200
  29. 3000
  30. 1200
  31. 2000
  32. 9000
  33. 700
  34. 1200
  35. 6300
  36. 2800
  37. 1000
  38. 800
  39. 1400
  40. 900

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