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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 396 · 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 54 × 92? (a) 450 (b) 45000 (c) 4500
  2. 2.Best estimate of 34 × 58? (a) 18000 (b) 1800 (c) 180
  3. 3.Best estimate of 44 × 31? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 143 + 229? (a) 100 (b) 500 (c) 300
  5. 5.Best estimate of 300 + 186? (a) 300 (b) 500 (c) 700
  6. 6.Best estimate of 670 + 481? (a) 1400 (b) 1200 (c) 1000
  7. 7.Best estimate of 564 + 125? (a) 700 (b) 900 (c) 500
  8. 8.Best estimate of 39 × 17? (a) 800 (b) 8000 (c) 80
  9. 9.Best estimate of 136 + 326? (a) 600 (b) 400 (c) 200
  10. 10.Best estimate of 688 + 172? (a) 700 (b) 900 (c) 1100
  11. 11.Best estimate of 96 × 26? (a) 30000 (b) 300 (c) 3000
  12. 12.Best estimate of 174 + 368? (a) 400 (b) 600 (c) 800
  13. 13.Best estimate of 209 + 284? (a) 300 (b) 500 (c) 700
  14. 14.Best estimate of 92 × 59? (a) 5400 (b) 54000 (c) 540
  15. 15.Best estimate of 84 × 12? (a) 800 (b) 80 (c) 8000
  16. 16.Best estimate of 79 × 12? (a) 800 (b) 8000 (c) 80
  17. 17.Best estimate of 87 × 77? (a) 7200 (b) 72000 (c) 720
  18. 18.Best estimate of 545 + 204? (a) 500 (b) 900 (c) 700
  19. 19.Best estimate of 477 + 243? (a) 700 (b) 500 (c) 900
  20. 20.Best estimate of 827 + 347? (a) 900 (b) 1100 (c) 1300
  21. 21.Best estimate of 31 × 52? (a) 1500 (b) 150 (c) 15000
  22. 22.Best estimate of 29 × 22? (a) 6000 (b) 60 (c) 600
  23. 23.Best estimate of 682 + 517? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 348 + 411? (a) 900 (b) 500 (c) 700
  25. 25.Best estimate of 81 × 58? (a) 480 (b) 48000 (c) 4800
  26. 26.Best estimate of 315 + 354? (a) 900 (b) 500 (c) 700
  27. 27.Best estimate of 14 × 69? (a) 7000 (b) 70 (c) 700
  28. 28.Best estimate of 20 × 48? (a) 10000 (b) 1000 (c) 100
  29. 29.Best estimate of 12 × 32? (a) 300 (b) 3000 (c) 30
  30. 30.Best estimate of 62 × 77? (a) 48000 (b) 480 (c) 4800
  31. 31.Best estimate of 451 + 180? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 338 + 671? (a) 800 (b) 1200 (c) 1000
  33. 33.Best estimate of 79 × 86? (a) 7200 (b) 72000 (c) 720
  34. 34.Best estimate of 504 + 678? (a) 1200 (b) 1400 (c) 1000
  35. 35.Best estimate of 94 × 79? (a) 720 (b) 7200 (c) 72000
  36. 36.Best estimate of 584 + 298? (a) 900 (b) 700 (c) 1100
  37. 37.Best estimate of 238 + 334? (a) 500 (b) 700 (c) 300
  38. 38.Best estimate of 37 × 88? (a) 360 (b) 3600 (c) 36000
  39. 39.Best estimate of 63 × 37? (a) 2400 (b) 24000 (c) 240
  40. 40.Best estimate of 198 + 559? (a) 1000 (b) 600 (c) 800

Answer key

  1. 4500
  2. 1800
  3. 1200
  4. 300
  5. 500
  6. 1200
  7. 700
  8. 800
  9. 400
  10. 900
  11. 3000
  12. 600
  13. 500
  14. 5400
  15. 800
  16. 800
  17. 7200
  18. 700
  19. 700
  20. 1100
  21. 1500
  22. 600
  23. 1200
  24. 700
  25. 4800
  26. 700
  27. 700
  28. 1000
  29. 300
  30. 4800
  31. 700
  32. 1000
  33. 7200
  34. 1200
  35. 7200
  36. 900
  37. 500
  38. 3600
  39. 2400
  40. 800

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