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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 482 · 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 51 × 63? (a) 30000 (b) 3000 (c) 300
  2. 2.Best estimate of 653 + 638? (a) 1300 (b) 1100 (c) 1500
  3. 3.Best estimate of 238 + 207? (a) 400 (b) 200 (c) 600
  4. 4.Best estimate of 30 × 54? (a) 150 (b) 15000 (c) 1500
  5. 5.Best estimate of 57 × 59? (a) 36000 (b) 3600 (c) 360
  6. 6.Best estimate of 34 × 42? (a) 1200 (b) 12000 (c) 120
  7. 7.Best estimate of 32 × 56? (a) 18000 (b) 180 (c) 1800
  8. 8.Best estimate of 693 + 407? (a) 900 (b) 1300 (c) 1100
  9. 9.Best estimate of 851 + 706? (a) 1600 (b) 1400 (c) 1800
  10. 10.Best estimate of 669 + 795? (a) 1500 (b) 1700 (c) 1300
  11. 11.Best estimate of 339 + 270? (a) 400 (b) 600 (c) 800
  12. 12.Best estimate of 16 × 74? (a) 140 (b) 14000 (c) 1400
  13. 13.Best estimate of 19 × 28? (a) 6000 (b) 60 (c) 600
  14. 14.Best estimate of 762 + 164? (a) 1000 (b) 1200 (c) 800
  15. 15.Best estimate of 487 + 755? (a) 1500 (b) 1300 (c) 1100
  16. 16.Best estimate of 78 × 61? (a) 480 (b) 4800 (c) 48000
  17. 17.Best estimate of 825 + 505? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 17 × 66? (a) 1400 (b) 14000 (c) 140
  19. 19.Best estimate of 378 + 652? (a) 900 (b) 1300 (c) 1100
  20. 20.Best estimate of 98 × 46? (a) 50000 (b) 5000 (c) 500
  21. 21.Best estimate of 77 × 37? (a) 32000 (b) 320 (c) 3200
  22. 22.Best estimate of 21 × 42? (a) 80 (b) 8000 (c) 800
  23. 23.Best estimate of 342 + 876? (a) 1200 (b) 1400 (c) 1000
  24. 24.Best estimate of 490 + 226? (a) 500 (b) 700 (c) 900
  25. 25.Best estimate of 28 × 63? (a) 1800 (b) 18000 (c) 180
  26. 26.Best estimate of 869 + 794? (a) 1500 (b) 1900 (c) 1700
  27. 27.Best estimate of 93 × 83? (a) 7200 (b) 72000 (c) 720
  28. 28.Best estimate of 36 × 39? (a) 160 (b) 16000 (c) 1600
  29. 29.Best estimate of 39 × 43? (a) 1600 (b) 160 (c) 16000
  30. 30.Best estimate of 62 × 21? (a) 12000 (b) 120 (c) 1200
  31. 31.Best estimate of 317 + 156? (a) 500 (b) 700 (c) 300
  32. 32.Best estimate of 200 + 336? (a) 300 (b) 700 (c) 500
  33. 33.Best estimate of 78 × 58? (a) 48000 (b) 480 (c) 4800
  34. 34.Best estimate of 782 + 444? (a) 1200 (b) 1400 (c) 1000
  35. 35.Best estimate of 49 × 78? (a) 4000 (b) 40000 (c) 400
  36. 36.Best estimate of 785 + 858? (a) 1500 (b) 1900 (c) 1700
  37. 37.Best estimate of 77 × 63? (a) 4800 (b) 480 (c) 48000
  38. 38.Best estimate of 88 × 90? (a) 810 (b) 81000 (c) 8100
  39. 39.Best estimate of 562 + 649? (a) 1400 (b) 1200 (c) 1000
  40. 40.Best estimate of 849 + 225? (a) 800 (b) 1200 (c) 1000

Answer key

  1. 3000
  2. 1300
  3. 400
  4. 1500
  5. 3600
  6. 1200
  7. 1800
  8. 1100
  9. 1600
  10. 1500
  11. 600
  12. 1400
  13. 600
  14. 1000
  15. 1300
  16. 4800
  17. 1300
  18. 1400
  19. 1100
  20. 5000
  21. 3200
  22. 800
  23. 1200
  24. 700
  25. 1800
  26. 1700
  27. 7200
  28. 1600
  29. 1600
  30. 1200
  31. 500
  32. 500
  33. 4800
  34. 1200
  35. 4000
  36. 1700
  37. 4800
  38. 8100
  39. 1200
  40. 1000

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