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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 307 · 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 467 + 235? (a) 700 (b) 900 (c) 500
  2. 2.Best estimate of 245 + 304? (a) 700 (b) 500 (c) 300
  3. 3.Best estimate of 692 + 762? (a) 1500 (b) 1300 (c) 1700
  4. 4.Best estimate of 525 + 371? (a) 700 (b) 1100 (c) 900
  5. 5.Best estimate of 66 × 17? (a) 14000 (b) 1400 (c) 140
  6. 6.Best estimate of 23 × 44? (a) 800 (b) 80 (c) 8000
  7. 7.Best estimate of 66 × 58? (a) 42000 (b) 420 (c) 4200
  8. 8.Best estimate of 532 + 597? (a) 900 (b) 1300 (c) 1100
  9. 9.Best estimate of 16 × 20? (a) 400 (b) 40 (c) 4000
  10. 10.Best estimate of 142 + 159? (a) 300 (b) 100 (c) 500
  11. 11.Best estimate of 44 × 18? (a) 80 (b) 8000 (c) 800
  12. 12.Best estimate of 868 + 436? (a) 1500 (b) 1300 (c) 1100
  13. 13.Best estimate of 699 + 715? (a) 1200 (b) 1600 (c) 1400
  14. 14.Best estimate of 70 × 94? (a) 6300 (b) 63000 (c) 630
  15. 15.Best estimate of 83 × 36? (a) 32000 (b) 320 (c) 3200
  16. 16.Best estimate of 163 + 220? (a) 600 (b) 400 (c) 200
  17. 17.Best estimate of 242 + 507? (a) 500 (b) 700 (c) 900
  18. 18.Best estimate of 159 + 629? (a) 800 (b) 1000 (c) 600
  19. 19.Best estimate of 32 × 58? (a) 18000 (b) 180 (c) 1800
  20. 20.Best estimate of 51 × 97? (a) 500 (b) 50000 (c) 5000
  21. 21.Best estimate of 251 + 169? (a) 700 (b) 300 (c) 500
  22. 22.Best estimate of 74 × 63? (a) 420 (b) 42000 (c) 4200
  23. 23.Best estimate of 226 + 265? (a) 700 (b) 300 (c) 500
  24. 24.Best estimate of 26 × 36? (a) 1200 (b) 120 (c) 12000
  25. 25.Best estimate of 849 + 419? (a) 1000 (b) 1200 (c) 1400
  26. 26.Best estimate of 735 + 326? (a) 1000 (b) 1200 (c) 800
  27. 27.Best estimate of 30 × 88? (a) 27000 (b) 270 (c) 2700
  28. 28.Best estimate of 76 × 51? (a) 400 (b) 4000 (c) 40000
  29. 29.Best estimate of 96 × 80? (a) 800 (b) 80000 (c) 8000
  30. 30.Best estimate of 788 + 269? (a) 1300 (b) 900 (c) 1100
  31. 31.Best estimate of 839 + 804? (a) 1400 (b) 1600 (c) 1800
  32. 32.Best estimate of 26 × 43? (a) 12000 (b) 1200 (c) 120
  33. 33.Best estimate of 51 × 18? (a) 100 (b) 1000 (c) 10000
  34. 34.Best estimate of 688 + 563? (a) 1300 (b) 1500 (c) 1100
  35. 35.Best estimate of 78 × 66? (a) 5600 (b) 560 (c) 56000
  36. 36.Best estimate of 27 × 60? (a) 18000 (b) 180 (c) 1800
  37. 37.Best estimate of 525 + 244? (a) 700 (b) 900 (c) 500
  38. 38.Best estimate of 135 + 830? (a) 700 (b) 900 (c) 1100
  39. 39.Best estimate of 70 × 63? (a) 4200 (b) 420 (c) 42000
  40. 40.Best estimate of 53 × 46? (a) 25000 (b) 250 (c) 2500

Answer key

  1. 700
  2. 500
  3. 1500
  4. 900
  5. 1400
  6. 800
  7. 4200
  8. 1100
  9. 400
  10. 300
  11. 800
  12. 1300
  13. 1400
  14. 6300
  15. 3200
  16. 400
  17. 700
  18. 800
  19. 1800
  20. 5000
  21. 500
  22. 4200
  23. 500
  24. 1200
  25. 1200
  26. 1000
  27. 2700
  28. 4000
  29. 8000
  30. 1100
  31. 1600
  32. 1200
  33. 1000
  34. 1300
  35. 5600
  36. 1800
  37. 700
  38. 900
  39. 4200
  40. 2500

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