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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 496 · 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 21 × 14? (a) 20 (b) 200 (c) 2000
  2. 2.Best estimate of 440 + 830? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 786 + 366? (a) 1400 (b) 1200 (c) 1000
  4. 4.Best estimate of 46 × 36? (a) 200 (b) 20000 (c) 2000
  5. 5.Best estimate of 555 + 874? (a) 1700 (b) 1300 (c) 1500
  6. 6.Best estimate of 20 × 21? (a) 400 (b) 4000 (c) 40
  7. 7.Best estimate of 26 × 44? (a) 12000 (b) 120 (c) 1200
  8. 8.Best estimate of 494 + 182? (a) 700 (b) 900 (c) 500
  9. 9.Best estimate of 49 × 38? (a) 20000 (b) 200 (c) 2000
  10. 10.Best estimate of 313 + 615? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 737 + 470? (a) 1400 (b) 1200 (c) 1000
  12. 12.Best estimate of 29 × 32? (a) 9000 (b) 90 (c) 900
  13. 13.Best estimate of 176 + 421? (a) 600 (b) 800 (c) 400
  14. 14.Best estimate of 13 × 46? (a) 50 (b) 500 (c) 5000
  15. 15.Best estimate of 97 × 77? (a) 8000 (b) 80000 (c) 800
  16. 16.Best estimate of 61 × 22? (a) 120 (b) 1200 (c) 12000
  17. 17.Best estimate of 92 × 37? (a) 3600 (b) 360 (c) 36000
  18. 18.Best estimate of 97 × 78? (a) 800 (b) 80000 (c) 8000
  19. 19.Best estimate of 16 × 86? (a) 1800 (b) 18000 (c) 180
  20. 20.Best estimate of 546 + 225? (a) 500 (b) 900 (c) 700
  21. 21.Best estimate of 59 × 81? (a) 48000 (b) 480 (c) 4800
  22. 22.Best estimate of 86 × 67? (a) 6300 (b) 63000 (c) 630
  23. 23.Best estimate of 167 + 566? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 50 × 97? (a) 5000 (b) 50000 (c) 500
  25. 25.Best estimate of 135 + 558? (a) 700 (b) 500 (c) 900
  26. 26.Best estimate of 12 × 42? (a) 40 (b) 400 (c) 4000
  27. 27.Best estimate of 723 + 740? (a) 1400 (b) 1600 (c) 1200
  28. 28.Best estimate of 73 × 46? (a) 350 (b) 35000 (c) 3500
  29. 29.Best estimate of 31 × 21? (a) 6000 (b) 60 (c) 600
  30. 30.Best estimate of 874 + 781? (a) 1500 (b) 1900 (c) 1700
  31. 31.Best estimate of 50 × 77? (a) 4000 (b) 40000 (c) 400
  32. 32.Best estimate of 37 × 20? (a) 8000 (b) 800 (c) 80
  33. 33.Best estimate of 16 × 14? (a) 200 (b) 2000 (c) 20
  34. 34.Best estimate of 807 + 465? (a) 1500 (b) 1100 (c) 1300
  35. 35.Best estimate of 713 + 672? (a) 1200 (b) 1600 (c) 1400
  36. 36.Best estimate of 92 × 24? (a) 1800 (b) 18000 (c) 180
  37. 37.Best estimate of 674 + 547? (a) 1400 (b) 1200 (c) 1000
  38. 38.Best estimate of 47 × 43? (a) 20000 (b) 2000 (c) 200
  39. 39.Best estimate of 601 + 248? (a) 600 (b) 800 (c) 1000
  40. 40.Best estimate of 425 + 241? (a) 600 (b) 400 (c) 800

Answer key

  1. 200
  2. 1200
  3. 1200
  4. 2000
  5. 1500
  6. 400
  7. 1200
  8. 700
  9. 2000
  10. 900
  11. 1200
  12. 900
  13. 600
  14. 500
  15. 8000
  16. 1200
  17. 3600
  18. 8000
  19. 1800
  20. 700
  21. 4800
  22. 6300
  23. 800
  24. 5000
  25. 700
  26. 400
  27. 1400
  28. 3500
  29. 600
  30. 1700
  31. 4000
  32. 800
  33. 200
  34. 1300
  35. 1400
  36. 1800
  37. 1200
  38. 2000
  39. 800
  40. 600

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