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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 552 · 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 77 × 53? (a) 4000 (b) 400 (c) 40000
  2. 2.Best estimate of 51 × 60? (a) 30000 (b) 300 (c) 3000
  3. 3.Best estimate of 291 + 604? (a) 1100 (b) 900 (c) 700
  4. 4.Best estimate of 24 × 22? (a) 400 (b) 40 (c) 4000
  5. 5.Best estimate of 284 + 121? (a) 400 (b) 600 (c) 200
  6. 6.Best estimate of 700 + 632? (a) 1100 (b) 1500 (c) 1300
  7. 7.Best estimate of 185 + 169? (a) 600 (b) 200 (c) 400
  8. 8.Best estimate of 670 + 251? (a) 1000 (b) 800 (c) 1200
  9. 9.Best estimate of 92 × 83? (a) 720 (b) 7200 (c) 72000
  10. 10.Best estimate of 588 + 216? (a) 1000 (b) 600 (c) 800
  11. 11.Best estimate of 43 × 39? (a) 160 (b) 1600 (c) 16000
  12. 12.Best estimate of 486 + 610? (a) 1300 (b) 900 (c) 1100
  13. 13.Best estimate of 175 + 310? (a) 300 (b) 500 (c) 700
  14. 14.Best estimate of 96 × 49? (a) 5000 (b) 50000 (c) 500
  15. 15.Best estimate of 90 × 88? (a) 81000 (b) 8100 (c) 810
  16. 16.Best estimate of 58 × 71? (a) 42000 (b) 420 (c) 4200
  17. 17.Best estimate of 42 × 57? (a) 240 (b) 2400 (c) 24000
  18. 18.Best estimate of 20 × 36? (a) 8000 (b) 80 (c) 800
  19. 19.Best estimate of 416 + 157? (a) 800 (b) 600 (c) 400
  20. 20.Best estimate of 17 × 67? (a) 1400 (b) 14000 (c) 140
  21. 21.Best estimate of 147 + 803? (a) 700 (b) 900 (c) 1100
  22. 22.Best estimate of 63 × 50? (a) 30000 (b) 3000 (c) 300
  23. 23.Best estimate of 753 + 780? (a) 1600 (b) 1400 (c) 1800
  24. 24.Best estimate of 16 × 33? (a) 600 (b) 6000 (c) 60
  25. 25.Best estimate of 652 + 677? (a) 1400 (b) 1200 (c) 1600
  26. 26.Best estimate of 78 × 43? (a) 320 (b) 3200 (c) 32000
  27. 27.Best estimate of 61 × 87? (a) 5400 (b) 540 (c) 54000
  28. 28.Best estimate of 16 × 31? (a) 600 (b) 6000 (c) 60
  29. 29.Best estimate of 298 + 319? (a) 600 (b) 800 (c) 400
  30. 30.Best estimate of 559 + 458? (a) 1300 (b) 1100 (c) 900
  31. 31.Best estimate of 77 × 49? (a) 40000 (b) 4000 (c) 400
  32. 32.Best estimate of 400 + 361? (a) 1000 (b) 800 (c) 600
  33. 33.Best estimate of 249 + 531? (a) 700 (b) 500 (c) 900
  34. 34.Best estimate of 26 × 46? (a) 15000 (b) 150 (c) 1500
  35. 35.Best estimate of 457 + 502? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 766 + 122? (a) 900 (b) 700 (c) 1100
  37. 37.Best estimate of 238 + 623? (a) 800 (b) 600 (c) 1000
  38. 38.Best estimate of 214 + 478? (a) 900 (b) 700 (c) 500
  39. 39.Best estimate of 86 × 74? (a) 6300 (b) 630 (c) 63000
  40. 40.Best estimate of 83 × 92? (a) 72000 (b) 720 (c) 7200

Answer key

  1. 4000
  2. 3000
  3. 900
  4. 400
  5. 400
  6. 1300
  7. 400
  8. 1000
  9. 7200
  10. 800
  11. 1600
  12. 1100
  13. 500
  14. 5000
  15. 8100
  16. 4200
  17. 2400
  18. 800
  19. 600
  20. 1400
  21. 900
  22. 3000
  23. 1600
  24. 600
  25. 1400
  26. 3200
  27. 5400
  28. 600
  29. 600
  30. 1100
  31. 4000
  32. 800
  33. 700
  34. 1500
  35. 1000
  36. 900
  37. 800
  38. 700
  39. 6300
  40. 7200

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