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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 471 · 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 313 + 488? (a) 800 (b) 600 (c) 1000
  2. 2.Best estimate of 211 + 522? (a) 500 (b) 700 (c) 900
  3. 3.Best estimate of 437 + 338? (a) 700 (b) 500 (c) 900
  4. 4.Best estimate of 44 × 87? (a) 3600 (b) 36000 (c) 360
  5. 5.Best estimate of 13 × 16? (a) 2000 (b) 20 (c) 200
  6. 6.Best estimate of 26 × 39? (a) 12000 (b) 120 (c) 1200
  7. 7.Best estimate of 823 + 263? (a) 1100 (b) 900 (c) 1300
  8. 8.Best estimate of 293 + 516? (a) 600 (b) 1000 (c) 800
  9. 9.Best estimate of 470 + 504? (a) 800 (b) 1200 (c) 1000
  10. 10.Best estimate of 31 × 47? (a) 150 (b) 1500 (c) 15000
  11. 11.Best estimate of 139 + 411? (a) 500 (b) 700 (c) 300
  12. 12.Best estimate of 383 + 231? (a) 400 (b) 600 (c) 800
  13. 13.Best estimate of 251 + 666? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 254 + 301? (a) 800 (b) 400 (c) 600
  15. 15.Best estimate of 70 × 87? (a) 63000 (b) 6300 (c) 630
  16. 16.Best estimate of 81 × 61? (a) 480 (b) 48000 (c) 4800
  17. 17.Best estimate of 93 × 19? (a) 180 (b) 1800 (c) 18000
  18. 18.Best estimate of 86 × 68? (a) 63000 (b) 6300 (c) 630
  19. 19.Best estimate of 56 × 49? (a) 3000 (b) 300 (c) 30000
  20. 20.Best estimate of 659 + 863? (a) 1400 (b) 1600 (c) 1800
  21. 21.Best estimate of 63 × 19? (a) 1200 (b) 120 (c) 12000
  22. 22.Best estimate of 393 + 723? (a) 1100 (b) 1300 (c) 900
  23. 23.Best estimate of 140 + 361? (a) 700 (b) 300 (c) 500
  24. 24.Best estimate of 811 + 417? (a) 1400 (b) 1200 (c) 1000
  25. 25.Best estimate of 216 + 180? (a) 400 (b) 200 (c) 600
  26. 26.Best estimate of 375 + 348? (a) 500 (b) 900 (c) 700
  27. 27.Best estimate of 211 + 370? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 79 × 27? (a) 240 (b) 2400 (c) 24000
  29. 29.Best estimate of 30 × 89? (a) 27000 (b) 270 (c) 2700
  30. 30.Best estimate of 830 + 691? (a) 1700 (b) 1500 (c) 1300
  31. 31.Best estimate of 510 + 605? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 346 + 223? (a) 700 (b) 300 (c) 500
  33. 33.Best estimate of 203 + 265? (a) 500 (b) 300 (c) 700
  34. 34.Best estimate of 24 × 48? (a) 1000 (b) 10000 (c) 100
  35. 35.Best estimate of 46 × 28? (a) 15000 (b) 150 (c) 1500
  36. 36.Best estimate of 92 × 39? (a) 36000 (b) 3600 (c) 360
  37. 37.Best estimate of 71 × 36? (a) 2800 (b) 280 (c) 28000
  38. 38.Best estimate of 54 × 56? (a) 3000 (b) 30000 (c) 300
  39. 39.Best estimate of 409 + 493? (a) 900 (b) 1100 (c) 700
  40. 40.Best estimate of 89 × 20? (a) 18000 (b) 1800 (c) 180

Answer key

  1. 800
  2. 700
  3. 700
  4. 3600
  5. 200
  6. 1200
  7. 1100
  8. 800
  9. 1000
  10. 1500
  11. 500
  12. 600
  13. 1000
  14. 600
  15. 6300
  16. 4800
  17. 1800
  18. 6300
  19. 3000
  20. 1600
  21. 1200
  22. 1100
  23. 500
  24. 1200
  25. 400
  26. 700
  27. 600
  28. 2400
  29. 2700
  30. 1500
  31. 1100
  32. 500
  33. 500
  34. 1000
  35. 1500
  36. 3600
  37. 2800
  38. 3000
  39. 900
  40. 1800

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