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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 906 · 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 454 + 804? (a) 1100 (b) 1300 (c) 1500
  2. 2.Best estimate of 68 × 26? (a) 2100 (b) 21000 (c) 210
  3. 3.Best estimate of 21 × 84? (a) 16000 (b) 1600 (c) 160
  4. 4.Best estimate of 53 × 67? (a) 350 (b) 3500 (c) 35000
  5. 5.Best estimate of 72 × 98? (a) 700 (b) 70000 (c) 7000
  6. 6.Best estimate of 39 × 16? (a) 80 (b) 8000 (c) 800
  7. 7.Best estimate of 17 × 13? (a) 200 (b) 2000 (c) 20
  8. 8.Best estimate of 240 + 342? (a) 700 (b) 300 (c) 500
  9. 9.Best estimate of 179 + 236? (a) 400 (b) 600 (c) 200
  10. 10.Best estimate of 64 × 28? (a) 18000 (b) 180 (c) 1800
  11. 11.Best estimate of 296 + 581? (a) 700 (b) 1100 (c) 900
  12. 12.Best estimate of 66 × 21? (a) 140 (b) 14000 (c) 1400
  13. 13.Best estimate of 42 × 26? (a) 12000 (b) 120 (c) 1200
  14. 14.Best estimate of 33 × 60? (a) 180 (b) 18000 (c) 1800
  15. 15.Best estimate of 343 + 308? (a) 600 (b) 800 (c) 400
  16. 16.Best estimate of 87 × 46? (a) 450 (b) 4500 (c) 45000
  17. 17.Best estimate of 36 × 13? (a) 4000 (b) 40 (c) 400
  18. 18.Best estimate of 94 × 13? (a) 9000 (b) 90 (c) 900
  19. 19.Best estimate of 68 × 77? (a) 560 (b) 56000 (c) 5600
  20. 20.Best estimate of 16 × 63? (a) 12000 (b) 120 (c) 1200
  21. 21.Best estimate of 599 + 591? (a) 1400 (b) 1000 (c) 1200
  22. 22.Best estimate of 32 × 60? (a) 18000 (b) 1800 (c) 180
  23. 23.Best estimate of 96 × 38? (a) 400 (b) 4000 (c) 40000
  24. 24.Best estimate of 153 + 298? (a) 500 (b) 300 (c) 700
  25. 25.Best estimate of 20 × 30? (a) 6000 (b) 60 (c) 600
  26. 26.Best estimate of 76 × 98? (a) 8000 (b) 800 (c) 80000
  27. 27.Best estimate of 337 + 374? (a) 700 (b) 500 (c) 900
  28. 28.Best estimate of 503 + 149? (a) 800 (b) 400 (c) 600
  29. 29.Best estimate of 12 × 56? (a) 6000 (b) 600 (c) 60
  30. 30.Best estimate of 434 + 249? (a) 400 (b) 800 (c) 600
  31. 31.Best estimate of 51 × 97? (a) 500 (b) 5000 (c) 50000
  32. 32.Best estimate of 807 + 237? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 435 + 391? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 79 × 16? (a) 1600 (b) 16000 (c) 160
  35. 35.Best estimate of 76 × 32? (a) 240 (b) 2400 (c) 24000
  36. 36.Best estimate of 405 + 670? (a) 900 (b) 1100 (c) 1300
  37. 37.Best estimate of 554 + 342? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 613 + 713? (a) 1500 (b) 1300 (c) 1100
  39. 39.Best estimate of 296 + 773? (a) 1300 (b) 1100 (c) 900
  40. 40.Best estimate of 747 + 634? (a) 1100 (b) 1500 (c) 1300

Answer key

  1. 1300
  2. 2100
  3. 1600
  4. 3500
  5. 7000
  6. 800
  7. 200
  8. 500
  9. 400
  10. 1800
  11. 900
  12. 1400
  13. 1200
  14. 1800
  15. 600
  16. 4500
  17. 400
  18. 900
  19. 5600
  20. 1200
  21. 1200
  22. 1800
  23. 4000
  24. 500
  25. 600
  26. 8000
  27. 700
  28. 600
  29. 600
  30. 600
  31. 5000
  32. 1000
  33. 800
  34. 1600
  35. 2400
  36. 1100
  37. 900
  38. 1300
  39. 1100
  40. 1300

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