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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 506 · 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 26 × 24? (a) 6000 (b) 600 (c) 60
  2. 2.Best estimate of 37 × 28? (a) 1200 (b) 12000 (c) 120
  3. 3.Best estimate of 242 + 474? (a) 900 (b) 500 (c) 700
  4. 4.Best estimate of 402 + 225? (a) 800 (b) 400 (c) 600
  5. 5.Best estimate of 17 × 60? (a) 1200 (b) 120 (c) 12000
  6. 6.Best estimate of 749 + 618? (a) 1300 (b) 1100 (c) 1500
  7. 7.Best estimate of 165 + 327? (a) 700 (b) 500 (c) 300
  8. 8.Best estimate of 811 + 857? (a) 1700 (b) 1500 (c) 1900
  9. 9.Best estimate of 137 + 622? (a) 500 (b) 700 (c) 900
  10. 10.Best estimate of 66 × 54? (a) 3500 (b) 350 (c) 35000
  11. 11.Best estimate of 53 × 80? (a) 40000 (b) 4000 (c) 400
  12. 12.Best estimate of 646 + 874? (a) 1500 (b) 1700 (c) 1300
  13. 13.Best estimate of 76 × 74? (a) 5600 (b) 56000 (c) 560
  14. 14.Best estimate of 60 × 36? (a) 2400 (b) 24000 (c) 240
  15. 15.Best estimate of 503 + 673? (a) 1000 (b) 1400 (c) 1200
  16. 16.Best estimate of 522 + 245? (a) 900 (b) 500 (c) 700
  17. 17.Best estimate of 23 × 68? (a) 1400 (b) 14000 (c) 140
  18. 18.Best estimate of 31 × 48? (a) 1500 (b) 15000 (c) 150
  19. 19.Best estimate of 38 × 12? (a) 400 (b) 40 (c) 4000
  20. 20.Best estimate of 538 + 367? (a) 1100 (b) 900 (c) 700
  21. 21.Best estimate of 38 × 86? (a) 36000 (b) 3600 (c) 360
  22. 22.Best estimate of 82 × 12? (a) 8000 (b) 800 (c) 80
  23. 23.Best estimate of 91 × 21? (a) 1800 (b) 180 (c) 18000
  24. 24.Best estimate of 764 + 492? (a) 1100 (b) 1500 (c) 1300
  25. 25.Best estimate of 63 × 31? (a) 18000 (b) 1800 (c) 180
  26. 26.Best estimate of 73 × 16? (a) 14000 (b) 140 (c) 1400
  27. 27.Best estimate of 397 + 667? (a) 900 (b) 1300 (c) 1100
  28. 28.Best estimate of 84 × 14? (a) 80 (b) 800 (c) 8000
  29. 29.Best estimate of 88 × 19? (a) 18000 (b) 180 (c) 1800
  30. 30.Best estimate of 756 + 282? (a) 1100 (b) 900 (c) 1300
  31. 31.Best estimate of 408 + 338? (a) 700 (b) 900 (c) 500
  32. 32.Best estimate of 17 × 21? (a) 40 (b) 4000 (c) 400
  33. 33.Best estimate of 268 + 140? (a) 600 (b) 400 (c) 200
  34. 34.Best estimate of 608 + 451? (a) 900 (b) 1100 (c) 1300
  35. 35.Best estimate of 123 + 300? (a) 200 (b) 600 (c) 400
  36. 36.Best estimate of 713 + 260? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 84 × 38? (a) 3200 (b) 32000 (c) 320
  38. 38.Best estimate of 36 × 13? (a) 4000 (b) 400 (c) 40
  39. 39.Best estimate of 83 × 44? (a) 3200 (b) 32000 (c) 320
  40. 40.Best estimate of 501 + 257? (a) 600 (b) 1000 (c) 800

Answer key

  1. 600
  2. 1200
  3. 700
  4. 600
  5. 1200
  6. 1300
  7. 500
  8. 1700
  9. 700
  10. 3500
  11. 4000
  12. 1500
  13. 5600
  14. 2400
  15. 1200
  16. 700
  17. 1400
  18. 1500
  19. 400
  20. 900
  21. 3600
  22. 800
  23. 1800
  24. 1300
  25. 1800
  26. 1400
  27. 1100
  28. 800
  29. 1800
  30. 1100
  31. 700
  32. 400
  33. 400
  34. 1100
  35. 400
  36. 1000
  37. 3200
  38. 400
  39. 3200
  40. 800

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