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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 279 · 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 255 + 651? (a) 1000 (b) 1200 (c) 800
  2. 2.Best estimate of 62 × 90? (a) 5400 (b) 540 (c) 54000
  3. 3.Best estimate of 677 + 585? (a) 1500 (b) 1300 (c) 1100
  4. 4.Best estimate of 361 + 287? (a) 500 (b) 900 (c) 700
  5. 5.Best estimate of 727 + 870? (a) 1400 (b) 1600 (c) 1800
  6. 6.Best estimate of 269 + 449? (a) 700 (b) 900 (c) 500
  7. 7.Best estimate of 447 + 670? (a) 900 (b) 1300 (c) 1100
  8. 8.Best estimate of 873 + 454? (a) 1200 (b) 1600 (c) 1400
  9. 9.Best estimate of 698 + 711? (a) 1200 (b) 1600 (c) 1400
  10. 10.Best estimate of 73 × 30? (a) 21000 (b) 2100 (c) 210
  11. 11.Best estimate of 67 × 34? (a) 2100 (b) 210 (c) 21000
  12. 12.Best estimate of 640 + 642? (a) 1400 (b) 1000 (c) 1200
  13. 13.Best estimate of 70 × 71? (a) 490 (b) 4900 (c) 49000
  14. 14.Best estimate of 33 × 23? (a) 600 (b) 60 (c) 6000
  15. 15.Best estimate of 449 + 762? (a) 1000 (b) 1400 (c) 1200
  16. 16.Best estimate of 269 + 669? (a) 800 (b) 1200 (c) 1000
  17. 17.Best estimate of 740 + 123? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 625 + 505? (a) 900 (b) 1300 (c) 1100
  19. 19.Best estimate of 387 + 779? (a) 1400 (b) 1200 (c) 1000
  20. 20.Best estimate of 41 × 89? (a) 36000 (b) 360 (c) 3600
  21. 21.Best estimate of 244 + 567? (a) 800 (b) 600 (c) 1000
  22. 22.Best estimate of 783 + 654? (a) 1500 (b) 1700 (c) 1300
  23. 23.Best estimate of 82 × 19? (a) 1600 (b) 16000 (c) 160
  24. 24.Best estimate of 564 + 741? (a) 1100 (b) 1500 (c) 1300
  25. 25.Best estimate of 653 + 257? (a) 800 (b) 1200 (c) 1000
  26. 26.Best estimate of 69 × 16? (a) 14000 (b) 1400 (c) 140
  27. 27.Best estimate of 40 × 72? (a) 2800 (b) 28000 (c) 280
  28. 28.Best estimate of 762 + 413? (a) 1200 (b) 1000 (c) 1400
  29. 29.Best estimate of 771 + 334? (a) 1300 (b) 1100 (c) 900
  30. 30.Best estimate of 27 × 27? (a) 900 (b) 90 (c) 9000
  31. 31.Best estimate of 647 + 518? (a) 900 (b) 1100 (c) 1300
  32. 32.Best estimate of 16 × 28? (a) 6000 (b) 600 (c) 60
  33. 33.Best estimate of 185 + 690? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 24 × 96? (a) 2000 (b) 20000 (c) 200
  35. 35.Best estimate of 23 × 71? (a) 14000 (b) 1400 (c) 140
  36. 36.Best estimate of 90 × 49? (a) 4500 (b) 450 (c) 45000
  37. 37.Best estimate of 403 + 338? (a) 900 (b) 700 (c) 500
  38. 38.Best estimate of 593 + 323? (a) 1100 (b) 900 (c) 700
  39. 39.Best estimate of 74 × 28? (a) 2100 (b) 210 (c) 21000
  40. 40.Best estimate of 728 + 174? (a) 700 (b) 900 (c) 1100

Answer key

  1. 1000
  2. 5400
  3. 1300
  4. 700
  5. 1600
  6. 700
  7. 1100
  8. 1400
  9. 1400
  10. 2100
  11. 2100
  12. 1200
  13. 4900
  14. 600
  15. 1200
  16. 1000
  17. 800
  18. 1100
  19. 1200
  20. 3600
  21. 800
  22. 1500
  23. 1600
  24. 1300
  25. 1000
  26. 1400
  27. 2800
  28. 1200
  29. 1100
  30. 900
  31. 1100
  32. 600
  33. 900
  34. 2000
  35. 1400
  36. 4500
  37. 700
  38. 900
  39. 2100
  40. 900

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