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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 557 · 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 732 + 211? (a) 900 (b) 1100 (c) 700
  2. 2.Best estimate of 685 + 458? (a) 1400 (b) 1000 (c) 1200
  3. 3.Best estimate of 14 × 76? (a) 800 (b) 8000 (c) 80
  4. 4.Best estimate of 26 × 61? (a) 1800 (b) 180 (c) 18000
  5. 5.Best estimate of 735 + 285? (a) 800 (b) 1200 (c) 1000
  6. 6.Best estimate of 38 × 78? (a) 320 (b) 3200 (c) 32000
  7. 7.Best estimate of 867 + 241? (a) 1300 (b) 1100 (c) 900
  8. 8.Best estimate of 22 × 39? (a) 800 (b) 80 (c) 8000
  9. 9.Best estimate of 29 × 61? (a) 1800 (b) 18000 (c) 180
  10. 10.Best estimate of 62 × 76? (a) 480 (b) 4800 (c) 48000
  11. 11.Best estimate of 68 × 46? (a) 350 (b) 35000 (c) 3500
  12. 12.Best estimate of 90 × 42? (a) 3600 (b) 360 (c) 36000
  13. 13.Best estimate of 495 + 751? (a) 1100 (b) 1300 (c) 1500
  14. 14.Best estimate of 452 + 439? (a) 900 (b) 700 (c) 1100
  15. 15.Best estimate of 90 × 41? (a) 360 (b) 3600 (c) 36000
  16. 16.Best estimate of 121 + 136? (a) 200 (b) 400 (c) 0
  17. 17.Best estimate of 259 + 306? (a) 400 (b) 800 (c) 600
  18. 18.Best estimate of 13 × 42? (a) 400 (b) 40 (c) 4000
  19. 19.Best estimate of 66 × 31? (a) 210 (b) 21000 (c) 2100
  20. 20.Best estimate of 273 + 405? (a) 500 (b) 900 (c) 700
  21. 21.Best estimate of 56 × 67? (a) 4200 (b) 420 (c) 42000
  22. 22.Best estimate of 792 + 173? (a) 1000 (b) 800 (c) 1200
  23. 23.Best estimate of 479 + 584? (a) 1100 (b) 1300 (c) 900
  24. 24.Best estimate of 17 × 70? (a) 140 (b) 1400 (c) 14000
  25. 25.Best estimate of 38 × 86? (a) 3600 (b) 36000 (c) 360
  26. 26.Best estimate of 401 + 645? (a) 1000 (b) 800 (c) 1200
  27. 27.Best estimate of 91 × 36? (a) 3600 (b) 360 (c) 36000
  28. 28.Best estimate of 44 × 87? (a) 360 (b) 36000 (c) 3600
  29. 29.Best estimate of 67 × 82? (a) 560 (b) 56000 (c) 5600
  30. 30.Best estimate of 682 + 498? (a) 1000 (b) 1200 (c) 1400
  31. 31.Best estimate of 809 + 659? (a) 1300 (b) 1500 (c) 1700
  32. 32.Best estimate of 431 + 701? (a) 1100 (b) 1300 (c) 900
  33. 33.Best estimate of 652 + 704? (a) 1400 (b) 1200 (c) 1600
  34. 34.Best estimate of 36 × 74? (a) 28000 (b) 2800 (c) 280
  35. 35.Best estimate of 24 × 31? (a) 6000 (b) 600 (c) 60
  36. 36.Best estimate of 34 × 21? (a) 6000 (b) 60 (c) 600
  37. 37.Best estimate of 39 × 22? (a) 800 (b) 80 (c) 8000
  38. 38.Best estimate of 137 + 219? (a) 300 (b) 500 (c) 100
  39. 39.Best estimate of 143 + 252? (a) 600 (b) 200 (c) 400
  40. 40.Best estimate of 156 + 297? (a) 700 (b) 500 (c) 300

Answer key

  1. 900
  2. 1200
  3. 800
  4. 1800
  5. 1000
  6. 3200
  7. 1100
  8. 800
  9. 1800
  10. 4800
  11. 3500
  12. 3600
  13. 1300
  14. 900
  15. 3600
  16. 200
  17. 600
  18. 400
  19. 2100
  20. 700
  21. 4200
  22. 1000
  23. 1100
  24. 1400
  25. 3600
  26. 1000
  27. 3600
  28. 3600
  29. 5600
  30. 1200
  31. 1500
  32. 1100
  33. 1400
  34. 2800
  35. 600
  36. 600
  37. 800
  38. 300
  39. 400
  40. 500

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