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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 326 · 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 23 × 64? (a) 12000 (b) 1200 (c) 120
  2. 2.Best estimate of 810 + 239? (a) 1200 (b) 1000 (c) 800
  3. 3.Best estimate of 477 + 336? (a) 800 (b) 600 (c) 1000
  4. 4.Best estimate of 80 × 66? (a) 56000 (b) 560 (c) 5600
  5. 5.Best estimate of 22 × 54? (a) 1000 (b) 100 (c) 10000
  6. 6.Best estimate of 78 × 47? (a) 4000 (b) 40000 (c) 400
  7. 7.Best estimate of 507 + 573? (a) 1300 (b) 900 (c) 1100
  8. 8.Best estimate of 568 + 311? (a) 1100 (b) 900 (c) 700
  9. 9.Best estimate of 301 + 730? (a) 1200 (b) 1000 (c) 800
  10. 10.Best estimate of 90 × 51? (a) 4500 (b) 45000 (c) 450
  11. 11.Best estimate of 17 × 86? (a) 180 (b) 18000 (c) 1800
  12. 12.Best estimate of 395 + 272? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 262 + 574? (a) 700 (b) 1100 (c) 900
  14. 14.Best estimate of 868 + 855? (a) 1600 (b) 2000 (c) 1800
  15. 15.Best estimate of 543 + 769? (a) 1100 (b) 1500 (c) 1300
  16. 16.Best estimate of 96 × 22? (a) 20000 (b) 2000 (c) 200
  17. 17.Best estimate of 694 + 766? (a) 1500 (b) 1700 (c) 1300
  18. 18.Best estimate of 91 × 81? (a) 72000 (b) 720 (c) 7200
  19. 19.Best estimate of 125 + 319? (a) 600 (b) 200 (c) 400
  20. 20.Best estimate of 34 × 52? (a) 15000 (b) 1500 (c) 150
  21. 21.Best estimate of 557 + 265? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 28 × 26? (a) 9000 (b) 900 (c) 90
  23. 23.Best estimate of 73 × 70? (a) 4900 (b) 49000 (c) 490
  24. 24.Best estimate of 731 + 646? (a) 1500 (b) 1300 (c) 1100
  25. 25.Best estimate of 16 × 67? (a) 1400 (b) 14000 (c) 140
  26. 26.Best estimate of 46 × 76? (a) 4000 (b) 40000 (c) 400
  27. 27.Best estimate of 300 + 844? (a) 900 (b) 1100 (c) 1300
  28. 28.Best estimate of 833 + 332? (a) 1300 (b) 1100 (c) 900
  29. 29.Best estimate of 79 × 36? (a) 320 (b) 32000 (c) 3200
  30. 30.Best estimate of 21 × 12? (a) 20 (b) 2000 (c) 200
  31. 31.Best estimate of 88 × 67? (a) 6300 (b) 630 (c) 63000
  32. 32.Best estimate of 24 × 89? (a) 180 (b) 1800 (c) 18000
  33. 33.Best estimate of 498 + 741? (a) 1400 (b) 1200 (c) 1000
  34. 34.Best estimate of 203 + 535? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 74 × 49? (a) 3500 (b) 35000 (c) 350
  36. 36.Best estimate of 177 + 353? (a) 800 (b) 400 (c) 600
  37. 37.Best estimate of 20 × 44? (a) 8000 (b) 800 (c) 80
  38. 38.Best estimate of 633 + 294? (a) 700 (b) 1100 (c) 900
  39. 39.Best estimate of 662 + 211? (a) 700 (b) 900 (c) 1100
  40. 40.Best estimate of 539 + 652? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 1200
  2. 1000
  3. 800
  4. 5600
  5. 1000
  6. 4000
  7. 1100
  8. 900
  9. 1000
  10. 4500
  11. 1800
  12. 700
  13. 900
  14. 1800
  15. 1300
  16. 2000
  17. 1500
  18. 7200
  19. 400
  20. 1500
  21. 900
  22. 900
  23. 4900
  24. 1300
  25. 1400
  26. 4000
  27. 1100
  28. 1100
  29. 3200
  30. 200
  31. 6300
  32. 1800
  33. 1200
  34. 700
  35. 3500
  36. 600
  37. 800
  38. 900
  39. 900
  40. 1200

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