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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 681 · 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 80 × 82? (a) 640 (b) 64000 (c) 6400
  2. 2.Best estimate of 29 × 67? (a) 21000 (b) 210 (c) 2100
  3. 3.Best estimate of 748 + 571? (a) 1500 (b) 1300 (c) 1100
  4. 4.Best estimate of 30 × 12? (a) 300 (b) 3000 (c) 30
  5. 5.Best estimate of 607 + 347? (a) 1100 (b) 900 (c) 700
  6. 6.Best estimate of 426 + 765? (a) 1000 (b) 1400 (c) 1200
  7. 7.Best estimate of 82 × 83? (a) 6400 (b) 64000 (c) 640
  8. 8.Best estimate of 94 × 13? (a) 900 (b) 90 (c) 9000
  9. 9.Best estimate of 36 × 64? (a) 2400 (b) 240 (c) 24000
  10. 10.Best estimate of 488 + 626? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 34 × 56? (a) 18000 (b) 180 (c) 1800
  12. 12.Best estimate of 60 × 96? (a) 600 (b) 60000 (c) 6000
  13. 13.Best estimate of 300 + 267? (a) 800 (b) 600 (c) 400
  14. 14.Best estimate of 868 + 384? (a) 1500 (b) 1300 (c) 1100
  15. 15.Best estimate of 22 × 64? (a) 12000 (b) 120 (c) 1200
  16. 16.Best estimate of 14 × 64? (a) 6000 (b) 600 (c) 60
  17. 17.Best estimate of 98 × 83? (a) 80000 (b) 8000 (c) 800
  18. 18.Best estimate of 514 + 257? (a) 600 (b) 800 (c) 1000
  19. 19.Best estimate of 13 × 44? (a) 400 (b) 40 (c) 4000
  20. 20.Best estimate of 859 + 587? (a) 1700 (b) 1500 (c) 1300
  21. 21.Best estimate of 19 × 24? (a) 4000 (b) 400 (c) 40
  22. 22.Best estimate of 337 + 384? (a) 500 (b) 900 (c) 700
  23. 23.Best estimate of 48 × 57? (a) 3000 (b) 30000 (c) 300
  24. 24.Best estimate of 76 × 76? (a) 64000 (b) 6400 (c) 640
  25. 25.Best estimate of 14 × 17? (a) 2000 (b) 200 (c) 20
  26. 26.Best estimate of 23 × 67? (a) 14000 (b) 140 (c) 1400
  27. 27.Best estimate of 381 + 247? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 691 + 743? (a) 1400 (b) 1600 (c) 1200
  29. 29.Best estimate of 505 + 141? (a) 800 (b) 600 (c) 400
  30. 30.Best estimate of 160 + 142? (a) 100 (b) 500 (c) 300
  31. 31.Best estimate of 21 × 78? (a) 1600 (b) 16000 (c) 160
  32. 32.Best estimate of 41 × 91? (a) 36000 (b) 360 (c) 3600
  33. 33.Best estimate of 398 + 399? (a) 800 (b) 600 (c) 1000
  34. 34.Best estimate of 184 + 214? (a) 600 (b) 400 (c) 200
  35. 35.Best estimate of 48 × 21? (a) 10000 (b) 100 (c) 1000
  36. 36.Best estimate of 61 × 32? (a) 1800 (b) 18000 (c) 180
  37. 37.Best estimate of 56 × 67? (a) 42000 (b) 4200 (c) 420
  38. 38.Best estimate of 573 + 591? (a) 1000 (b) 1200 (c) 1400
  39. 39.Best estimate of 126 + 164? (a) 100 (b) 500 (c) 300
  40. 40.Best estimate of 26 × 34? (a) 90 (b) 9000 (c) 900

Answer key

  1. 6400
  2. 2100
  3. 1300
  4. 300
  5. 900
  6. 1200
  7. 6400
  8. 900
  9. 2400
  10. 1100
  11. 1800
  12. 6000
  13. 600
  14. 1300
  15. 1200
  16. 600
  17. 8000
  18. 800
  19. 400
  20. 1500
  21. 400
  22. 700
  23. 3000
  24. 6400
  25. 200
  26. 1400
  27. 600
  28. 1400
  29. 600
  30. 300
  31. 1600
  32. 3600
  33. 800
  34. 400
  35. 1000
  36. 1800
  37. 4200
  38. 1200
  39. 300
  40. 900

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