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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 538 · 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 66 × 68? (a) 4900 (b) 490 (c) 49000
  2. 2.Best estimate of 618 + 245? (a) 1000 (b) 800 (c) 600
  3. 3.Best estimate of 28 × 61? (a) 1800 (b) 180 (c) 18000
  4. 4.Best estimate of 80 × 68? (a) 56000 (b) 5600 (c) 560
  5. 5.Best estimate of 81 × 74? (a) 5600 (b) 56000 (c) 560
  6. 6.Best estimate of 36 × 97? (a) 4000 (b) 400 (c) 40000
  7. 7.Best estimate of 226 + 813? (a) 1000 (b) 800 (c) 1200
  8. 8.Best estimate of 74 × 87? (a) 63000 (b) 630 (c) 6300
  9. 9.Best estimate of 144 + 877? (a) 1000 (b) 800 (c) 1200
  10. 10.Best estimate of 551 + 462? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 76 × 32? (a) 2400 (b) 24000 (c) 240
  12. 12.Best estimate of 47 × 23? (a) 1000 (b) 10000 (c) 100
  13. 13.Best estimate of 33 × 30? (a) 9000 (b) 900 (c) 90
  14. 14.Best estimate of 449 + 145? (a) 300 (b) 500 (c) 700
  15. 15.Best estimate of 428 + 484? (a) 700 (b) 900 (c) 1100
  16. 16.Best estimate of 32 × 36? (a) 120 (b) 12000 (c) 1200
  17. 17.Best estimate of 747 + 588? (a) 1500 (b) 1100 (c) 1300
  18. 18.Best estimate of 94 × 44? (a) 36000 (b) 3600 (c) 360
  19. 19.Best estimate of 56 × 58? (a) 3600 (b) 36000 (c) 360
  20. 20.Best estimate of 16 × 34? (a) 6000 (b) 60 (c) 600
  21. 21.Best estimate of 428 + 642? (a) 800 (b) 1200 (c) 1000
  22. 22.Best estimate of 37 × 70? (a) 28000 (b) 2800 (c) 280
  23. 23.Best estimate of 63 × 14? (a) 60 (b) 6000 (c) 600
  24. 24.Best estimate of 24 × 19? (a) 400 (b) 4000 (c) 40
  25. 25.Best estimate of 372 + 178? (a) 800 (b) 400 (c) 600
  26. 26.Best estimate of 71 × 74? (a) 490 (b) 4900 (c) 49000
  27. 27.Best estimate of 31 × 88? (a) 2700 (b) 27000 (c) 270
  28. 28.Best estimate of 90 × 96? (a) 90000 (b) 900 (c) 9000
  29. 29.Best estimate of 305 + 229? (a) 700 (b) 500 (c) 300
  30. 30.Best estimate of 301 + 318? (a) 600 (b) 400 (c) 800
  31. 31.Best estimate of 440 + 760? (a) 1400 (b) 1000 (c) 1200
  32. 32.Best estimate of 719 + 860? (a) 1600 (b) 1800 (c) 1400
  33. 33.Best estimate of 519 + 273? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 595 + 598? (a) 1000 (b) 1400 (c) 1200
  35. 35.Best estimate of 26 × 57? (a) 180 (b) 18000 (c) 1800
  36. 36.Best estimate of 87 × 93? (a) 81000 (b) 810 (c) 8100
  37. 37.Best estimate of 63 × 32? (a) 18000 (b) 1800 (c) 180
  38. 38.Best estimate of 324 + 712? (a) 1200 (b) 800 (c) 1000
  39. 39.Best estimate of 77 × 59? (a) 48000 (b) 4800 (c) 480
  40. 40.Best estimate of 309 + 419? (a) 500 (b) 900 (c) 700

Answer key

  1. 4900
  2. 800
  3. 1800
  4. 5600
  5. 5600
  6. 4000
  7. 1000
  8. 6300
  9. 1000
  10. 1100
  11. 2400
  12. 1000
  13. 900
  14. 500
  15. 900
  16. 1200
  17. 1300
  18. 3600
  19. 3600
  20. 600
  21. 1000
  22. 2800
  23. 600
  24. 400
  25. 600
  26. 4900
  27. 2700
  28. 9000
  29. 500
  30. 600
  31. 1200
  32. 1600
  33. 800
  34. 1200
  35. 1800
  36. 8100
  37. 1800
  38. 1000
  39. 4800
  40. 700

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