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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 353 · 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 452 + 154? (a) 500 (b) 700 (c) 900
  2. 2.Best estimate of 487 + 818? (a) 1300 (b) 1500 (c) 1100
  3. 3.Best estimate of 342 + 300? (a) 800 (b) 600 (c) 400
  4. 4.Best estimate of 354 + 671? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 61 × 67? (a) 4200 (b) 420 (c) 42000
  6. 6.Best estimate of 91 × 41? (a) 3600 (b) 360 (c) 36000
  7. 7.Best estimate of 532 + 598? (a) 1300 (b) 1100 (c) 900
  8. 8.Best estimate of 32 × 94? (a) 27000 (b) 2700 (c) 270
  9. 9.Best estimate of 38 × 76? (a) 320 (b) 32000 (c) 3200
  10. 10.Best estimate of 89 × 23? (a) 1800 (b) 180 (c) 18000
  11. 11.Best estimate of 416 + 460? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 528 + 195? (a) 700 (b) 500 (c) 900
  13. 13.Best estimate of 505 + 327? (a) 800 (b) 1000 (c) 600
  14. 14.Best estimate of 93 × 59? (a) 54000 (b) 540 (c) 5400
  15. 15.Best estimate of 751 + 764? (a) 1400 (b) 1600 (c) 1800
  16. 16.Best estimate of 42 × 39? (a) 16000 (b) 160 (c) 1600
  17. 17.Best estimate of 62 × 54? (a) 300 (b) 3000 (c) 30000
  18. 18.Best estimate of 184 + 379? (a) 600 (b) 800 (c) 400
  19. 19.Best estimate of 140 + 842? (a) 1100 (b) 900 (c) 700
  20. 20.Best estimate of 13 × 54? (a) 500 (b) 50 (c) 5000
  21. 21.Best estimate of 360 + 588? (a) 1200 (b) 1000 (c) 800
  22. 22.Best estimate of 41 × 26? (a) 1200 (b) 12000 (c) 120
  23. 23.Best estimate of 70 × 31? (a) 210 (b) 2100 (c) 21000
  24. 24.Best estimate of 40 × 52? (a) 2000 (b) 200 (c) 20000
  25. 25.Best estimate of 79 × 43? (a) 32000 (b) 3200 (c) 320
  26. 26.Best estimate of 72 × 67? (a) 49000 (b) 490 (c) 4900
  27. 27.Best estimate of 760 + 712? (a) 1700 (b) 1500 (c) 1300
  28. 28.Best estimate of 168 + 491? (a) 700 (b) 900 (c) 500
  29. 29.Best estimate of 12 × 51? (a) 5000 (b) 500 (c) 50
  30. 30.Best estimate of 90 × 96? (a) 90000 (b) 900 (c) 9000
  31. 31.Best estimate of 554 + 372? (a) 1200 (b) 1000 (c) 800
  32. 32.Best estimate of 56 × 64? (a) 3600 (b) 360 (c) 36000
  33. 33.Best estimate of 724 + 390? (a) 1100 (b) 900 (c) 1300
  34. 34.Best estimate of 74 × 20? (a) 1400 (b) 14000 (c) 140
  35. 35.Best estimate of 304 + 451? (a) 800 (b) 600 (c) 1000
  36. 36.Best estimate of 26 × 23? (a) 600 (b) 6000 (c) 60
  37. 37.Best estimate of 803 + 625? (a) 1600 (b) 1400 (c) 1200
  38. 38.Best estimate of 46 × 89? (a) 4500 (b) 45000 (c) 450
  39. 39.Best estimate of 406 + 605? (a) 1200 (b) 1000 (c) 800
  40. 40.Best estimate of 33 × 96? (a) 3000 (b) 300 (c) 30000

Answer key

  1. 700
  2. 1300
  3. 600
  4. 1100
  5. 4200
  6. 3600
  7. 1100
  8. 2700
  9. 3200
  10. 1800
  11. 900
  12. 700
  13. 800
  14. 5400
  15. 1600
  16. 1600
  17. 3000
  18. 600
  19. 900
  20. 500
  21. 1000
  22. 1200
  23. 2100
  24. 2000
  25. 3200
  26. 4900
  27. 1500
  28. 700
  29. 500
  30. 9000
  31. 1000
  32. 3600
  33. 1100
  34. 1400
  35. 800
  36. 600
  37. 1400
  38. 4500
  39. 1000
  40. 3000

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