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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 118 · 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 527 + 870? (a) 1200 (b) 1600 (c) 1400
  2. 2.Best estimate of 14 × 42? (a) 40 (b) 4000 (c) 400
  3. 3.Best estimate of 81 × 53? (a) 4000 (b) 40000 (c) 400
  4. 4.Best estimate of 81 × 41? (a) 3200 (b) 32000 (c) 320
  5. 5.Best estimate of 255 + 777? (a) 900 (b) 1100 (c) 1300
  6. 6.Best estimate of 193 + 512? (a) 700 (b) 900 (c) 500
  7. 7.Best estimate of 48 × 69? (a) 3500 (b) 35000 (c) 350
  8. 8.Best estimate of 78 × 23? (a) 160 (b) 1600 (c) 16000
  9. 9.Best estimate of 208 + 592? (a) 600 (b) 1000 (c) 800
  10. 10.Best estimate of 76 × 17? (a) 1600 (b) 16000 (c) 160
  11. 11.Best estimate of 47 × 82? (a) 400 (b) 40000 (c) 4000
  12. 12.Best estimate of 311 + 212? (a) 700 (b) 500 (c) 300
  13. 13.Best estimate of 454 + 580? (a) 1300 (b) 1100 (c) 900
  14. 14.Best estimate of 74 × 66? (a) 4900 (b) 49000 (c) 490
  15. 15.Best estimate of 52 × 13? (a) 500 (b) 50 (c) 5000
  16. 16.Best estimate of 356 + 304? (a) 500 (b) 900 (c) 700
  17. 17.Best estimate of 76 × 51? (a) 400 (b) 4000 (c) 40000
  18. 18.Best estimate of 66 × 36? (a) 280 (b) 28000 (c) 2800
  19. 19.Best estimate of 58 × 13? (a) 60 (b) 600 (c) 6000
  20. 20.Best estimate of 210 + 534? (a) 700 (b) 500 (c) 900
  21. 21.Best estimate of 545 + 394? (a) 1100 (b) 700 (c) 900
  22. 22.Best estimate of 31 × 20? (a) 600 (b) 6000 (c) 60
  23. 23.Best estimate of 59 × 57? (a) 3600 (b) 36000 (c) 360
  24. 24.Best estimate of 21 × 78? (a) 1600 (b) 16000 (c) 160
  25. 25.Best estimate of 36 × 64? (a) 2400 (b) 24000 (c) 240
  26. 26.Best estimate of 93 × 32? (a) 2700 (b) 270 (c) 27000
  27. 27.Best estimate of 760 + 648? (a) 1600 (b) 1400 (c) 1200
  28. 28.Best estimate of 33 × 16? (a) 60 (b) 600 (c) 6000
  29. 29.Best estimate of 158 + 670? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 275 + 867? (a) 1200 (b) 1400 (c) 1000
  31. 31.Best estimate of 206 + 628? (a) 800 (b) 1000 (c) 600
  32. 32.Best estimate of 852 + 574? (a) 1700 (b) 1500 (c) 1300
  33. 33.Best estimate of 78 × 67? (a) 560 (b) 56000 (c) 5600
  34. 34.Best estimate of 277 + 337? (a) 600 (b) 800 (c) 400
  35. 35.Best estimate of 564 + 275? (a) 700 (b) 900 (c) 1100
  36. 36.Best estimate of 76 × 36? (a) 320 (b) 3200 (c) 32000
  37. 37.Best estimate of 876 + 522? (a) 1600 (b) 1400 (c) 1200
  38. 38.Best estimate of 20 × 56? (a) 12000 (b) 1200 (c) 120
  39. 39.Best estimate of 642 + 827? (a) 1400 (b) 1200 (c) 1600
  40. 40.Best estimate of 426 + 383? (a) 800 (b) 1000 (c) 600

Answer key

  1. 1400
  2. 400
  3. 4000
  4. 3200
  5. 1100
  6. 700
  7. 3500
  8. 1600
  9. 800
  10. 1600
  11. 4000
  12. 500
  13. 1100
  14. 4900
  15. 500
  16. 700
  17. 4000
  18. 2800
  19. 600
  20. 700
  21. 900
  22. 600
  23. 3600
  24. 1600
  25. 2400
  26. 2700
  27. 1400
  28. 600
  29. 900
  30. 1200
  31. 800
  32. 1500
  33. 5600
  34. 600
  35. 900
  36. 3200
  37. 1400
  38. 1200
  39. 1400
  40. 800

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