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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 108 · 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 371 + 858? (a) 1500 (b) 1100 (c) 1300
  2. 2.Best estimate of 98 × 27? (a) 300 (b) 30000 (c) 3000
  3. 3.Best estimate of 587 + 203? (a) 1000 (b) 800 (c) 600
  4. 4.Best estimate of 542 + 744? (a) 1200 (b) 1000 (c) 1400
  5. 5.Best estimate of 94 × 70? (a) 63000 (b) 6300 (c) 630
  6. 6.Best estimate of 751 + 588? (a) 1200 (b) 1400 (c) 1600
  7. 7.Best estimate of 808 + 692? (a) 1500 (b) 1700 (c) 1300
  8. 8.Best estimate of 37 × 27? (a) 120 (b) 12000 (c) 1200
  9. 9.Best estimate of 56 × 26? (a) 1800 (b) 18000 (c) 180
  10. 10.Best estimate of 96 × 28? (a) 3000 (b) 30000 (c) 300
  11. 11.Best estimate of 495 + 740? (a) 1200 (b) 1000 (c) 1400
  12. 12.Best estimate of 831 + 295? (a) 1100 (b) 900 (c) 1300
  13. 13.Best estimate of 859 + 289? (a) 1400 (b) 1200 (c) 1000
  14. 14.Best estimate of 187 + 716? (a) 1100 (b) 900 (c) 700
  15. 15.Best estimate of 284 + 185? (a) 300 (b) 500 (c) 700
  16. 16.Best estimate of 567 + 321? (a) 900 (b) 700 (c) 1100
  17. 17.Best estimate of 818 + 269? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 53 × 80? (a) 40000 (b) 4000 (c) 400
  19. 19.Best estimate of 68 × 34? (a) 210 (b) 2100 (c) 21000
  20. 20.Best estimate of 220 + 148? (a) 500 (b) 300 (c) 100
  21. 21.Best estimate of 16 × 90? (a) 1800 (b) 18000 (c) 180
  22. 22.Best estimate of 21 × 18? (a) 400 (b) 4000 (c) 40
  23. 23.Best estimate of 858 + 129? (a) 1200 (b) 800 (c) 1000
  24. 24.Best estimate of 96 × 57? (a) 60000 (b) 600 (c) 6000
  25. 25.Best estimate of 69 × 96? (a) 700 (b) 7000 (c) 70000
  26. 26.Best estimate of 200 + 854? (a) 1100 (b) 900 (c) 1300
  27. 27.Best estimate of 528 + 515? (a) 1000 (b) 1200 (c) 800
  28. 28.Best estimate of 376 + 428? (a) 1000 (b) 600 (c) 800
  29. 29.Best estimate of 483 + 154? (a) 700 (b) 500 (c) 900
  30. 30.Best estimate of 12 × 97? (a) 100 (b) 1000 (c) 10000
  31. 31.Best estimate of 366 + 185? (a) 600 (b) 800 (c) 400
  32. 32.Best estimate of 29 × 23? (a) 60 (b) 600 (c) 6000
  33. 33.Best estimate of 89 × 16? (a) 180 (b) 1800 (c) 18000
  34. 34.Best estimate of 216 + 404? (a) 600 (b) 400 (c) 800
  35. 35.Best estimate of 287 + 862? (a) 1000 (b) 1400 (c) 1200
  36. 36.Best estimate of 669 + 233? (a) 900 (b) 700 (c) 1100
  37. 37.Best estimate of 407 + 873? (a) 1100 (b) 1300 (c) 1500
  38. 38.Best estimate of 536 + 853? (a) 1600 (b) 1400 (c) 1200
  39. 39.Best estimate of 513 + 207? (a) 700 (b) 500 (c) 900
  40. 40.Best estimate of 226 + 641? (a) 800 (b) 1000 (c) 600

Answer key

  1. 1300
  2. 3000
  3. 800
  4. 1200
  5. 6300
  6. 1400
  7. 1500
  8. 1200
  9. 1800
  10. 3000
  11. 1200
  12. 1100
  13. 1200
  14. 900
  15. 500
  16. 900
  17. 1100
  18. 4000
  19. 2100
  20. 300
  21. 1800
  22. 400
  23. 1000
  24. 6000
  25. 7000
  26. 1100
  27. 1000
  28. 800
  29. 700
  30. 1000
  31. 600
  32. 600
  33. 1800
  34. 600
  35. 1200
  36. 900
  37. 1300
  38. 1400
  39. 700
  40. 800

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