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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 489 · 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 84 × 46? (a) 4000 (b) 40000 (c) 400
  2. 2.Best estimate of 464 + 170? (a) 700 (b) 900 (c) 500
  3. 3.Best estimate of 666 + 556? (a) 1500 (b) 1100 (c) 1300
  4. 4.Best estimate of 17 × 62? (a) 120 (b) 1200 (c) 12000
  5. 5.Best estimate of 22 × 76? (a) 160 (b) 16000 (c) 1600
  6. 6.Best estimate of 89 × 16? (a) 18000 (b) 1800 (c) 180
  7. 7.Best estimate of 680 + 349? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 56 × 93? (a) 54000 (b) 540 (c) 5400
  9. 9.Best estimate of 868 + 288? (a) 1400 (b) 1200 (c) 1000
  10. 10.Best estimate of 784 + 429? (a) 1000 (b) 1400 (c) 1200
  11. 11.Best estimate of 86 × 16? (a) 18000 (b) 180 (c) 1800
  12. 12.Best estimate of 18 × 13? (a) 2000 (b) 20 (c) 200
  13. 13.Best estimate of 44 × 27? (a) 12000 (b) 120 (c) 1200
  14. 14.Best estimate of 86 × 13? (a) 900 (b) 9000 (c) 90
  15. 15.Best estimate of 93 × 87? (a) 8100 (b) 810 (c) 81000
  16. 16.Best estimate of 448 + 514? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 262 + 311? (a) 800 (b) 600 (c) 400
  18. 18.Best estimate of 23 × 17? (a) 40 (b) 400 (c) 4000
  19. 19.Best estimate of 96 × 13? (a) 10000 (b) 1000 (c) 100
  20. 20.Best estimate of 830 + 596? (a) 1400 (b) 1600 (c) 1200
  21. 21.Best estimate of 20 × 86? (a) 1800 (b) 18000 (c) 180
  22. 22.Best estimate of 309 + 733? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 56 × 73? (a) 4200 (b) 420 (c) 42000
  24. 24.Best estimate of 48 × 66? (a) 350 (b) 3500 (c) 35000
  25. 25.Best estimate of 266 + 422? (a) 500 (b) 900 (c) 700
  26. 26.Best estimate of 56 × 16? (a) 1200 (b) 12000 (c) 120
  27. 27.Best estimate of 89 × 43? (a) 36000 (b) 3600 (c) 360
  28. 28.Best estimate of 28 × 13? (a) 300 (b) 30 (c) 3000
  29. 29.Best estimate of 187 + 513? (a) 700 (b) 900 (c) 500
  30. 30.Best estimate of 225 + 236? (a) 600 (b) 200 (c) 400
  31. 31.Best estimate of 22 × 39? (a) 80 (b) 8000 (c) 800
  32. 32.Best estimate of 811 + 582? (a) 1600 (b) 1200 (c) 1400
  33. 33.Best estimate of 12 × 56? (a) 60 (b) 6000 (c) 600
  34. 34.Best estimate of 863 + 470? (a) 1400 (b) 1600 (c) 1200
  35. 35.Best estimate of 281 + 327? (a) 600 (b) 400 (c) 800
  36. 36.Best estimate of 37 × 24? (a) 800 (b) 8000 (c) 80
  37. 37.Best estimate of 130 + 187? (a) 300 (b) 500 (c) 100
  38. 38.Best estimate of 13 × 32? (a) 30 (b) 300 (c) 3000
  39. 39.Best estimate of 200 + 513? (a) 500 (b) 700 (c) 900
  40. 40.Best estimate of 415 + 671? (a) 1300 (b) 900 (c) 1100

Answer key

  1. 4000
  2. 700
  3. 1300
  4. 1200
  5. 1600
  6. 1800
  7. 1000
  8. 5400
  9. 1200
  10. 1200
  11. 1800
  12. 200
  13. 1200
  14. 900
  15. 8100
  16. 900
  17. 600
  18. 400
  19. 1000
  20. 1400
  21. 1800
  22. 1000
  23. 4200
  24. 3500
  25. 700
  26. 1200
  27. 3600
  28. 300
  29. 700
  30. 400
  31. 800
  32. 1400
  33. 600
  34. 1400
  35. 600
  36. 800
  37. 300
  38. 300
  39. 700
  40. 1100

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