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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 694 · 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 71 × 81? (a) 5600 (b) 56000 (c) 560
  2. 2.Best estimate of 438 + 303? (a) 500 (b) 700 (c) 900
  3. 3.Best estimate of 70 × 86? (a) 63000 (b) 6300 (c) 630
  4. 4.Best estimate of 704 + 488? (a) 1000 (b) 1400 (c) 1200
  5. 5.Best estimate of 519 + 212? (a) 900 (b) 500 (c) 700
  6. 6.Best estimate of 98 × 58? (a) 6000 (b) 600 (c) 60000
  7. 7.Best estimate of 413 + 567? (a) 800 (b) 1000 (c) 1200
  8. 8.Best estimate of 23 × 50? (a) 100 (b) 1000 (c) 10000
  9. 9.Best estimate of 229 + 252? (a) 700 (b) 500 (c) 300
  10. 10.Best estimate of 871 + 693? (a) 1600 (b) 1400 (c) 1800
  11. 11.Best estimate of 330 + 475? (a) 600 (b) 800 (c) 1000
  12. 12.Best estimate of 643 + 268? (a) 900 (b) 700 (c) 1100
  13. 13.Best estimate of 77 × 67? (a) 56000 (b) 560 (c) 5600
  14. 14.Best estimate of 251 + 783? (a) 1100 (b) 900 (c) 1300
  15. 15.Best estimate of 16 × 70? (a) 140 (b) 14000 (c) 1400
  16. 16.Best estimate of 768 + 763? (a) 1600 (b) 1800 (c) 1400
  17. 17.Best estimate of 70 × 81? (a) 5600 (b) 560 (c) 56000
  18. 18.Best estimate of 816 + 879? (a) 1700 (b) 1900 (c) 1500
  19. 19.Best estimate of 17 × 22? (a) 4000 (b) 400 (c) 40
  20. 20.Best estimate of 578 + 367? (a) 1000 (b) 800 (c) 1200
  21. 21.Best estimate of 237 + 775? (a) 800 (b) 1200 (c) 1000
  22. 22.Best estimate of 389 + 718? (a) 1100 (b) 1300 (c) 900
  23. 23.Best estimate of 50 × 18? (a) 10000 (b) 1000 (c) 100
  24. 24.Best estimate of 51 × 98? (a) 50000 (b) 500 (c) 5000
  25. 25.Best estimate of 649 + 612? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 604 + 476? (a) 900 (b) 1300 (c) 1100
  27. 27.Best estimate of 381 + 742? (a) 1100 (b) 1300 (c) 900
  28. 28.Best estimate of 698 + 391? (a) 1300 (b) 900 (c) 1100
  29. 29.Best estimate of 30 × 22? (a) 60 (b) 6000 (c) 600
  30. 30.Best estimate of 49 × 73? (a) 35000 (b) 350 (c) 3500
  31. 31.Best estimate of 93 × 26? (a) 27000 (b) 2700 (c) 270
  32. 32.Best estimate of 132 + 580? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 683 + 481? (a) 1400 (b) 1000 (c) 1200
  34. 34.Best estimate of 422 + 461? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 653 + 569? (a) 1100 (b) 1300 (c) 1500
  36. 36.Best estimate of 142 + 666? (a) 800 (b) 600 (c) 1000
  37. 37.Best estimate of 39 × 37? (a) 16000 (b) 160 (c) 1600
  38. 38.Best estimate of 239 + 351? (a) 600 (b) 400 (c) 800
  39. 39.Best estimate of 20 × 14? (a) 20 (b) 2000 (c) 200
  40. 40.Best estimate of 82 × 23? (a) 160 (b) 1600 (c) 16000

Answer key

  1. 5600
  2. 700
  3. 6300
  4. 1200
  5. 700
  6. 6000
  7. 1000
  8. 1000
  9. 500
  10. 1600
  11. 800
  12. 900
  13. 5600
  14. 1100
  15. 1400
  16. 1600
  17. 5600
  18. 1700
  19. 400
  20. 1000
  21. 1000
  22. 1100
  23. 1000
  24. 5000
  25. 1200
  26. 1100
  27. 1100
  28. 1100
  29. 600
  30. 3500
  31. 2700
  32. 700
  33. 1200
  34. 900
  35. 1300
  36. 800
  37. 1600
  38. 600
  39. 200
  40. 1600

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