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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 163 · 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 341 + 147? (a) 200 (b) 400 (c) 600
  2. 2.Best estimate of 64 × 12? (a) 6000 (b) 600 (c) 60
  3. 3.Best estimate of 531 + 233? (a) 900 (b) 700 (c) 500
  4. 4.Best estimate of 367 + 603? (a) 1000 (b) 1200 (c) 800
  5. 5.Best estimate of 634 + 584? (a) 1000 (b) 1400 (c) 1200
  6. 6.Best estimate of 61 × 12? (a) 600 (b) 60 (c) 6000
  7. 7.Best estimate of 62 × 97? (a) 600 (b) 6000 (c) 60000
  8. 8.Best estimate of 97 × 67? (a) 70000 (b) 7000 (c) 700
  9. 9.Best estimate of 430 + 673? (a) 1100 (b) 1300 (c) 900
  10. 10.Best estimate of 143 + 731? (a) 800 (b) 600 (c) 1000
  11. 11.Best estimate of 339 + 688? (a) 800 (b) 1200 (c) 1000
  12. 12.Best estimate of 751 + 169? (a) 800 (b) 1200 (c) 1000
  13. 13.Best estimate of 873 + 569? (a) 1300 (b) 1700 (c) 1500
  14. 14.Best estimate of 47 × 94? (a) 4500 (b) 450 (c) 45000
  15. 15.Best estimate of 588 + 265? (a) 900 (b) 700 (c) 1100
  16. 16.Best estimate of 123 + 661? (a) 600 (b) 800 (c) 1000
  17. 17.Best estimate of 88 × 67? (a) 630 (b) 6300 (c) 63000
  18. 18.Best estimate of 417 + 785? (a) 1400 (b) 1200 (c) 1000
  19. 19.Best estimate of 31 × 97? (a) 300 (b) 3000 (c) 30000
  20. 20.Best estimate of 192 + 539? (a) 900 (b) 700 (c) 500
  21. 21.Best estimate of 29 × 63? (a) 180 (b) 1800 (c) 18000
  22. 22.Best estimate of 293 + 223? (a) 500 (b) 300 (c) 700
  23. 23.Best estimate of 337 + 197? (a) 300 (b) 700 (c) 500
  24. 24.Best estimate of 46 × 69? (a) 350 (b) 35000 (c) 3500
  25. 25.Best estimate of 163 + 827? (a) 800 (b) 1000 (c) 1200
  26. 26.Best estimate of 56 × 37? (a) 24000 (b) 2400 (c) 240
  27. 27.Best estimate of 48 × 73? (a) 350 (b) 35000 (c) 3500
  28. 28.Best estimate of 78 × 87? (a) 7200 (b) 72000 (c) 720
  29. 29.Best estimate of 70 × 46? (a) 350 (b) 35000 (c) 3500
  30. 30.Best estimate of 86 × 18? (a) 1800 (b) 18000 (c) 180
  31. 31.Best estimate of 89 × 71? (a) 63000 (b) 630 (c) 6300
  32. 32.Best estimate of 93 × 42? (a) 3600 (b) 360 (c) 36000
  33. 33.Best estimate of 844 + 668? (a) 1700 (b) 1300 (c) 1500
  34. 34.Best estimate of 144 + 586? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 838 + 652? (a) 1300 (b) 1700 (c) 1500
  36. 36.Best estimate of 820 + 581? (a) 1400 (b) 1600 (c) 1200
  37. 37.Best estimate of 87 × 20? (a) 1800 (b) 180 (c) 18000
  38. 38.Best estimate of 409 + 729? (a) 1100 (b) 1300 (c) 900
  39. 39.Best estimate of 37 × 16? (a) 8000 (b) 80 (c) 800
  40. 40.Best estimate of 633 + 844? (a) 1600 (b) 1200 (c) 1400

Answer key

  1. 400
  2. 600
  3. 700
  4. 1000
  5. 1200
  6. 600
  7. 6000
  8. 7000
  9. 1100
  10. 800
  11. 1000
  12. 1000
  13. 1500
  14. 4500
  15. 900
  16. 800
  17. 6300
  18. 1200
  19. 3000
  20. 700
  21. 1800
  22. 500
  23. 500
  24. 3500
  25. 1000
  26. 2400
  27. 3500
  28. 7200
  29. 3500
  30. 1800
  31. 6300
  32. 3600
  33. 1500
  34. 700
  35. 1500
  36. 1400
  37. 1800
  38. 1100
  39. 800
  40. 1400

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