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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 387 · 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 82 × 46? (a) 40000 (b) 400 (c) 4000
  2. 2.Best estimate of 88 × 51? (a) 450 (b) 45000 (c) 4500
  3. 3.Best estimate of 164 + 489? (a) 900 (b) 700 (c) 500
  4. 4.Best estimate of 18 × 78? (a) 1600 (b) 16000 (c) 160
  5. 5.Best estimate of 61 × 91? (a) 540 (b) 5400 (c) 54000
  6. 6.Best estimate of 627 + 419? (a) 800 (b) 1200 (c) 1000
  7. 7.Best estimate of 294 + 634? (a) 700 (b) 900 (c) 1100
  8. 8.Best estimate of 80 × 18? (a) 16000 (b) 160 (c) 1600
  9. 9.Best estimate of 327 + 724? (a) 1000 (b) 800 (c) 1200
  10. 10.Best estimate of 52 × 50? (a) 2500 (b) 250 (c) 25000
  11. 11.Best estimate of 370 + 497? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 49 × 46? (a) 2500 (b) 25000 (c) 250
  13. 13.Best estimate of 769 + 783? (a) 1800 (b) 1600 (c) 1400
  14. 14.Best estimate of 252 + 306? (a) 600 (b) 800 (c) 400
  15. 15.Best estimate of 57 × 68? (a) 4200 (b) 42000 (c) 420
  16. 16.Best estimate of 321 + 456? (a) 800 (b) 1000 (c) 600
  17. 17.Best estimate of 296 + 149? (a) 200 (b) 600 (c) 400
  18. 18.Best estimate of 131 + 285? (a) 200 (b) 400 (c) 600
  19. 19.Best estimate of 59 × 90? (a) 540 (b) 54000 (c) 5400
  20. 20.Best estimate of 474 + 648? (a) 1300 (b) 900 (c) 1100
  21. 21.Best estimate of 56 × 94? (a) 5400 (b) 54000 (c) 540
  22. 22.Best estimate of 96 × 42? (a) 4000 (b) 40000 (c) 400
  23. 23.Best estimate of 160 + 344? (a) 300 (b) 500 (c) 700
  24. 24.Best estimate of 741 + 126? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 490 + 870? (a) 1600 (b) 1200 (c) 1400
  26. 26.Best estimate of 36 × 98? (a) 40000 (b) 400 (c) 4000
  27. 27.Best estimate of 26 × 22? (a) 6000 (b) 600 (c) 60
  28. 28.Best estimate of 38 × 84? (a) 32000 (b) 320 (c) 3200
  29. 29.Best estimate of 798 + 729? (a) 1500 (b) 1300 (c) 1700
  30. 30.Best estimate of 303 + 263? (a) 600 (b) 800 (c) 400
  31. 31.Best estimate of 125 + 172? (a) 300 (b) 500 (c) 100
  32. 32.Best estimate of 126 + 235? (a) 500 (b) 100 (c) 300
  33. 33.Best estimate of 611 + 497? (a) 1300 (b) 900 (c) 1100
  34. 34.Best estimate of 68 × 24? (a) 1400 (b) 14000 (c) 140
  35. 35.Best estimate of 18 × 20? (a) 4000 (b) 400 (c) 40
  36. 36.Best estimate of 87 × 36? (a) 3600 (b) 36000 (c) 360
  37. 37.Best estimate of 407 + 596? (a) 800 (b) 1200 (c) 1000
  38. 38.Best estimate of 169 + 486? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 651 + 809? (a) 1500 (b) 1700 (c) 1300
  40. 40.Best estimate of 26 × 82? (a) 240 (b) 24000 (c) 2400

Answer key

  1. 4000
  2. 4500
  3. 700
  4. 1600
  5. 5400
  6. 1000
  7. 900
  8. 1600
  9. 1000
  10. 2500
  11. 900
  12. 2500
  13. 1600
  14. 600
  15. 4200
  16. 800
  17. 400
  18. 400
  19. 5400
  20. 1100
  21. 5400
  22. 4000
  23. 500
  24. 800
  25. 1400
  26. 4000
  27. 600
  28. 3200
  29. 1500
  30. 600
  31. 300
  32. 300
  33. 1100
  34. 1400
  35. 400
  36. 3600
  37. 1000
  38. 700
  39. 1500
  40. 2400

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