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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 375 · 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 462 + 791? (a) 1500 (b) 1300 (c) 1100
  2. 2.Best estimate of 724 + 454? (a) 1400 (b) 1000 (c) 1200
  3. 3.Best estimate of 263 + 451? (a) 600 (b) 800 (c) 1000
  4. 4.Best estimate of 71 × 33? (a) 210 (b) 2100 (c) 21000
  5. 5.Best estimate of 504 + 129? (a) 600 (b) 400 (c) 800
  6. 6.Best estimate of 68 × 62? (a) 42000 (b) 4200 (c) 420
  7. 7.Best estimate of 76 × 81? (a) 640 (b) 64000 (c) 6400
  8. 8.Best estimate of 353 + 473? (a) 900 (b) 700 (c) 1100
  9. 9.Best estimate of 44 × 94? (a) 36000 (b) 360 (c) 3600
  10. 10.Best estimate of 184 + 144? (a) 300 (b) 500 (c) 100
  11. 11.Best estimate of 770 + 712? (a) 1300 (b) 1500 (c) 1700
  12. 12.Best estimate of 401 + 428? (a) 800 (b) 1000 (c) 600
  13. 13.Best estimate of 64 × 68? (a) 420 (b) 42000 (c) 4200
  14. 14.Best estimate of 792 + 345? (a) 1300 (b) 900 (c) 1100
  15. 15.Best estimate of 32 × 34? (a) 900 (b) 90 (c) 9000
  16. 16.Best estimate of 279 + 329? (a) 800 (b) 400 (c) 600
  17. 17.Best estimate of 561 + 424? (a) 1200 (b) 1000 (c) 800
  18. 18.Best estimate of 658 + 617? (a) 1300 (b) 1100 (c) 1500
  19. 19.Best estimate of 89 × 39? (a) 360 (b) 36000 (c) 3600
  20. 20.Best estimate of 385 + 868? (a) 1100 (b) 1500 (c) 1300
  21. 21.Best estimate of 21 × 23? (a) 4000 (b) 400 (c) 40
  22. 22.Best estimate of 94 × 83? (a) 720 (b) 72000 (c) 7200
  23. 23.Best estimate of 92 × 66? (a) 63000 (b) 630 (c) 6300
  24. 24.Best estimate of 570 + 757? (a) 1600 (b) 1400 (c) 1200
  25. 25.Best estimate of 276 + 618? (a) 900 (b) 1100 (c) 700
  26. 26.Best estimate of 67 × 24? (a) 1400 (b) 14000 (c) 140
  27. 27.Best estimate of 794 + 838? (a) 1800 (b) 1400 (c) 1600
  28. 28.Best estimate of 393 + 211? (a) 400 (b) 600 (c) 800
  29. 29.Best estimate of 251 + 864? (a) 1200 (b) 1400 (c) 1000
  30. 30.Best estimate of 37 × 97? (a) 4000 (b) 40000 (c) 400
  31. 31.Best estimate of 458 + 213? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 444 + 575? (a) 1000 (b) 1200 (c) 800
  33. 33.Best estimate of 814 + 337? (a) 1300 (b) 900 (c) 1100
  34. 34.Best estimate of 224 + 700? (a) 1100 (b) 900 (c) 700
  35. 35.Best estimate of 632 + 195? (a) 1000 (b) 800 (c) 600
  36. 36.Best estimate of 69 × 37? (a) 2800 (b) 280 (c) 28000
  37. 37.Best estimate of 40 × 66? (a) 28000 (b) 2800 (c) 280
  38. 38.Best estimate of 238 + 481? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 34 × 19? (a) 600 (b) 6000 (c) 60
  40. 40.Best estimate of 38 × 23? (a) 800 (b) 80 (c) 8000

Answer key

  1. 1300
  2. 1200
  3. 800
  4. 2100
  5. 600
  6. 4200
  7. 6400
  8. 900
  9. 3600
  10. 300
  11. 1500
  12. 800
  13. 4200
  14. 1100
  15. 900
  16. 600
  17. 1000
  18. 1300
  19. 3600
  20. 1300
  21. 400
  22. 7200
  23. 6300
  24. 1400
  25. 900
  26. 1400
  27. 1600
  28. 600
  29. 1200
  30. 4000
  31. 700
  32. 1000
  33. 1100
  34. 900
  35. 800
  36. 2800
  37. 2800
  38. 700
  39. 600
  40. 800

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