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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 663 · 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 23 × 72? (a) 1400 (b) 14000 (c) 140
  2. 2.Best estimate of 12 × 74? (a) 700 (b) 70 (c) 7000
  3. 3.Best estimate of 755 + 814? (a) 1800 (b) 1400 (c) 1600
  4. 4.Best estimate of 482 + 310? (a) 1000 (b) 600 (c) 800
  5. 5.Best estimate of 211 + 757? (a) 1000 (b) 800 (c) 1200
  6. 6.Best estimate of 96 × 91? (a) 9000 (b) 900 (c) 90000
  7. 7.Best estimate of 495 + 305? (a) 600 (b) 1000 (c) 800
  8. 8.Best estimate of 93 × 44? (a) 36000 (b) 360 (c) 3600
  9. 9.Best estimate of 30 × 31? (a) 900 (b) 9000 (c) 90
  10. 10.Best estimate of 408 + 329? (a) 700 (b) 900 (c) 500
  11. 11.Best estimate of 733 + 435? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 32 × 73? (a) 210 (b) 21000 (c) 2100
  13. 13.Best estimate of 180 + 315? (a) 700 (b) 500 (c) 300
  14. 14.Best estimate of 312 + 243? (a) 700 (b) 300 (c) 500
  15. 15.Best estimate of 621 + 146? (a) 500 (b) 900 (c) 700
  16. 16.Best estimate of 76 × 62? (a) 480 (b) 4800 (c) 48000
  17. 17.Best estimate of 272 + 478? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 188 + 812? (a) 1200 (b) 1000 (c) 800
  19. 19.Best estimate of 23 × 30? (a) 60 (b) 6000 (c) 600
  20. 20.Best estimate of 492 + 789? (a) 1500 (b) 1100 (c) 1300
  21. 21.Best estimate of 27 × 14? (a) 300 (b) 3000 (c) 30
  22. 22.Best estimate of 44 × 60? (a) 24000 (b) 240 (c) 2400
  23. 23.Best estimate of 327 + 593? (a) 900 (b) 1100 (c) 700
  24. 24.Best estimate of 36 × 66? (a) 280 (b) 28000 (c) 2800
  25. 25.Best estimate of 864 + 144? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 66 × 30? (a) 2100 (b) 210 (c) 21000
  27. 27.Best estimate of 51 × 12? (a) 500 (b) 50 (c) 5000
  28. 28.Best estimate of 76 × 40? (a) 32000 (b) 320 (c) 3200
  29. 29.Best estimate of 96 × 81? (a) 8000 (b) 80000 (c) 800
  30. 30.Best estimate of 593 + 880? (a) 1700 (b) 1500 (c) 1300
  31. 31.Best estimate of 26 × 60? (a) 18000 (b) 1800 (c) 180
  32. 32.Best estimate of 34 × 82? (a) 240 (b) 24000 (c) 2400
  33. 33.Best estimate of 858 + 675? (a) 1800 (b) 1600 (c) 1400
  34. 34.Best estimate of 80 × 17? (a) 1600 (b) 16000 (c) 160
  35. 35.Best estimate of 16 × 29? (a) 600 (b) 6000 (c) 60
  36. 36.Best estimate of 562 + 415? (a) 1200 (b) 800 (c) 1000
  37. 37.Best estimate of 97 × 56? (a) 600 (b) 6000 (c) 60000
  38. 38.Best estimate of 48 × 87? (a) 45000 (b) 4500 (c) 450
  39. 39.Best estimate of 149 + 289? (a) 200 (b) 400 (c) 600
  40. 40.Best estimate of 54 × 88? (a) 45000 (b) 4500 (c) 450

Answer key

  1. 1400
  2. 700
  3. 1600
  4. 800
  5. 1000
  6. 9000
  7. 800
  8. 3600
  9. 900
  10. 700
  11. 1100
  12. 2100
  13. 500
  14. 500
  15. 700
  16. 4800
  17. 800
  18. 1000
  19. 600
  20. 1300
  21. 300
  22. 2400
  23. 900
  24. 2800
  25. 1000
  26. 2100
  27. 500
  28. 3200
  29. 8000
  30. 1500
  31. 1800
  32. 2400
  33. 1600
  34. 1600
  35. 600
  36. 1000
  37. 6000
  38. 4500
  39. 400
  40. 4500

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