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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 335 · 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 79 × 76? (a) 6400 (b) 64000 (c) 640
  2. 2.Best estimate of 718 + 479? (a) 1400 (b) 1000 (c) 1200
  3. 3.Best estimate of 50 × 41? (a) 2000 (b) 200 (c) 20000
  4. 4.Best estimate of 42 × 31? (a) 12000 (b) 120 (c) 1200
  5. 5.Best estimate of 725 + 802? (a) 1700 (b) 1300 (c) 1500
  6. 6.Best estimate of 871 + 815? (a) 1700 (b) 1900 (c) 1500
  7. 7.Best estimate of 92 × 37? (a) 360 (b) 3600 (c) 36000
  8. 8.Best estimate of 87 × 87? (a) 8100 (b) 81000 (c) 810
  9. 9.Best estimate of 714 + 747? (a) 1400 (b) 1600 (c) 1200
  10. 10.Best estimate of 582 + 785? (a) 1200 (b) 1600 (c) 1400
  11. 11.Best estimate of 76 × 77? (a) 64000 (b) 640 (c) 6400
  12. 12.Best estimate of 182 + 489? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 844 + 440? (a) 1400 (b) 1200 (c) 1000
  14. 14.Best estimate of 71 × 37? (a) 2800 (b) 280 (c) 28000
  15. 15.Best estimate of 838 + 342? (a) 1300 (b) 1100 (c) 900
  16. 16.Best estimate of 30 × 57? (a) 1800 (b) 18000 (c) 180
  17. 17.Best estimate of 37 × 26? (a) 1200 (b) 12000 (c) 120
  18. 18.Best estimate of 57 × 42? (a) 240 (b) 2400 (c) 24000
  19. 19.Best estimate of 863 + 827? (a) 1700 (b) 1900 (c) 1500
  20. 20.Best estimate of 81 × 26? (a) 2400 (b) 240 (c) 24000
  21. 21.Best estimate of 56 × 51? (a) 3000 (b) 30000 (c) 300
  22. 22.Best estimate of 96 × 17? (a) 2000 (b) 20000 (c) 200
  23. 23.Best estimate of 395 + 832? (a) 1200 (b) 1400 (c) 1000
  24. 24.Best estimate of 779 + 861? (a) 1900 (b) 1700 (c) 1500
  25. 25.Best estimate of 81 × 83? (a) 640 (b) 64000 (c) 6400
  26. 26.Best estimate of 616 + 137? (a) 900 (b) 500 (c) 700
  27. 27.Best estimate of 342 + 795? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 63 × 96? (a) 6000 (b) 60000 (c) 600
  29. 29.Best estimate of 233 + 591? (a) 1000 (b) 600 (c) 800
  30. 30.Best estimate of 16 × 76? (a) 16000 (b) 160 (c) 1600
  31. 31.Best estimate of 86 × 40? (a) 3600 (b) 360 (c) 36000
  32. 32.Best estimate of 61 × 98? (a) 600 (b) 6000 (c) 60000
  33. 33.Best estimate of 93 × 90? (a) 810 (b) 8100 (c) 81000
  34. 34.Best estimate of 746 + 582? (a) 1100 (b) 1300 (c) 1500
  35. 35.Best estimate of 40 × 52? (a) 2000 (b) 200 (c) 20000
  36. 36.Best estimate of 34 × 18? (a) 6000 (b) 600 (c) 60
  37. 37.Best estimate of 36 × 69? (a) 28000 (b) 280 (c) 2800
  38. 38.Best estimate of 32 × 23? (a) 600 (b) 60 (c) 6000
  39. 39.Best estimate of 69 × 12? (a) 7000 (b) 70 (c) 700
  40. 40.Best estimate of 537 + 629? (a) 900 (b) 1300 (c) 1100

Answer key

  1. 6400
  2. 1200
  3. 2000
  4. 1200
  5. 1500
  6. 1700
  7. 3600
  8. 8100
  9. 1400
  10. 1400
  11. 6400
  12. 700
  13. 1200
  14. 2800
  15. 1100
  16. 1800
  17. 1200
  18. 2400
  19. 1700
  20. 2400
  21. 3000
  22. 2000
  23. 1200
  24. 1700
  25. 6400
  26. 700
  27. 1100
  28. 6000
  29. 800
  30. 1600
  31. 3600
  32. 6000
  33. 8100
  34. 1300
  35. 2000
  36. 600
  37. 2800
  38. 600
  39. 700
  40. 1100

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