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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 213 · 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 20 × 47? (a) 100 (b) 1000 (c) 10000
  2. 2.Best estimate of 123 + 153? (a) 500 (b) 100 (c) 300
  3. 3.Best estimate of 14 × 17? (a) 200 (b) 2000 (c) 20
  4. 4.Best estimate of 17 × 67? (a) 1400 (b) 140 (c) 14000
  5. 5.Best estimate of 633 + 820? (a) 1600 (b) 1400 (c) 1200
  6. 6.Best estimate of 61 × 96? (a) 60000 (b) 6000 (c) 600
  7. 7.Best estimate of 32 × 21? (a) 600 (b) 6000 (c) 60
  8. 8.Best estimate of 876 + 878? (a) 2000 (b) 1800 (c) 1600
  9. 9.Best estimate of 242 + 375? (a) 600 (b) 800 (c) 400
  10. 10.Best estimate of 12 × 84? (a) 800 (b) 80 (c) 8000
  11. 11.Best estimate of 124 + 487? (a) 800 (b) 600 (c) 400
  12. 12.Best estimate of 216 + 130? (a) 100 (b) 500 (c) 300
  13. 13.Best estimate of 76 × 26? (a) 24000 (b) 240 (c) 2400
  14. 14.Best estimate of 552 + 172? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 142 + 871? (a) 1000 (b) 1200 (c) 800
  16. 16.Best estimate of 766 + 595? (a) 1200 (b) 1400 (c) 1600
  17. 17.Best estimate of 96 × 51? (a) 5000 (b) 50000 (c) 500
  18. 18.Best estimate of 703 + 844? (a) 1700 (b) 1500 (c) 1300
  19. 19.Best estimate of 39 × 33? (a) 12000 (b) 1200 (c) 120
  20. 20.Best estimate of 14 × 21? (a) 20 (b) 2000 (c) 200
  21. 21.Best estimate of 863 + 645? (a) 1500 (b) 1700 (c) 1300
  22. 22.Best estimate of 24 × 83? (a) 160 (b) 1600 (c) 16000
  23. 23.Best estimate of 67 × 34? (a) 21000 (b) 210 (c) 2100
  24. 24.Best estimate of 243 + 153? (a) 600 (b) 200 (c) 400
  25. 25.Best estimate of 370 + 347? (a) 500 (b) 900 (c) 700
  26. 26.Best estimate of 30 × 46? (a) 150 (b) 15000 (c) 1500
  27. 27.Best estimate of 768 + 282? (a) 900 (b) 1100 (c) 1300
  28. 28.Best estimate of 239 + 410? (a) 600 (b) 800 (c) 400
  29. 29.Best estimate of 16 × 47? (a) 10000 (b) 1000 (c) 100
  30. 30.Best estimate of 71 × 98? (a) 70000 (b) 7000 (c) 700
  31. 31.Best estimate of 59 × 56? (a) 36000 (b) 360 (c) 3600
  32. 32.Best estimate of 326 + 867? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 387 + 183? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 232 + 599? (a) 800 (b) 600 (c) 1000
  35. 35.Best estimate of 13 × 51? (a) 500 (b) 50 (c) 5000
  36. 36.Best estimate of 13 × 61? (a) 600 (b) 60 (c) 6000
  37. 37.Best estimate of 281 + 292? (a) 600 (b) 400 (c) 800
  38. 38.Best estimate of 54 × 36? (a) 20000 (b) 2000 (c) 200
  39. 39.Best estimate of 262 + 836? (a) 1100 (b) 900 (c) 1300
  40. 40.Best estimate of 712 + 531? (a) 1000 (b) 1400 (c) 1200

Answer key

  1. 1000
  2. 300
  3. 200
  4. 1400
  5. 1400
  6. 6000
  7. 600
  8. 1800
  9. 600
  10. 800
  11. 600
  12. 300
  13. 2400
  14. 800
  15. 1000
  16. 1400
  17. 5000
  18. 1500
  19. 1200
  20. 200
  21. 1500
  22. 1600
  23. 2100
  24. 400
  25. 700
  26. 1500
  27. 1100
  28. 600
  29. 1000
  30. 7000
  31. 3600
  32. 1200
  33. 600
  34. 800
  35. 500
  36. 600
  37. 600
  38. 2000
  39. 1100
  40. 1200

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