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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 121 · 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 601 + 641? (a) 1200 (b) 1400 (c) 1000
  2. 2.Best estimate of 66 × 13? (a) 70 (b) 700 (c) 7000
  3. 3.Best estimate of 33 × 51? (a) 150 (b) 1500 (c) 15000
  4. 4.Best estimate of 92 × 36? (a) 36000 (b) 360 (c) 3600
  5. 5.Best estimate of 816 + 848? (a) 1800 (b) 1400 (c) 1600
  6. 6.Best estimate of 46 × 63? (a) 300 (b) 30000 (c) 3000
  7. 7.Best estimate of 278 + 289? (a) 400 (b) 800 (c) 600
  8. 8.Best estimate of 97 × 47? (a) 500 (b) 50000 (c) 5000
  9. 9.Best estimate of 18 × 26? (a) 6000 (b) 600 (c) 60
  10. 10.Best estimate of 18 × 92? (a) 18000 (b) 1800 (c) 180
  11. 11.Best estimate of 32 × 63? (a) 18000 (b) 1800 (c) 180
  12. 12.Best estimate of 34 × 38? (a) 12000 (b) 1200 (c) 120
  13. 13.Best estimate of 439 + 701? (a) 1300 (b) 1100 (c) 900
  14. 14.Best estimate of 84 × 88? (a) 72000 (b) 7200 (c) 720
  15. 15.Best estimate of 321 + 777? (a) 900 (b) 1300 (c) 1100
  16. 16.Best estimate of 305 + 330? (a) 600 (b) 400 (c) 800
  17. 17.Best estimate of 867 + 493? (a) 1400 (b) 1200 (c) 1600
  18. 18.Best estimate of 24 × 38? (a) 80 (b) 8000 (c) 800
  19. 19.Best estimate of 88 × 90? (a) 810 (b) 8100 (c) 81000
  20. 20.Best estimate of 752 + 300? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 78 × 96? (a) 800 (b) 8000 (c) 80000
  22. 22.Best estimate of 800 + 706? (a) 1700 (b) 1300 (c) 1500
  23. 23.Best estimate of 73 × 59? (a) 42000 (b) 4200 (c) 420
  24. 24.Best estimate of 288 + 204? (a) 500 (b) 700 (c) 300
  25. 25.Best estimate of 345 + 873? (a) 1400 (b) 1000 (c) 1200
  26. 26.Best estimate of 339 + 523? (a) 800 (b) 600 (c) 1000
  27. 27.Best estimate of 27 × 50? (a) 1500 (b) 15000 (c) 150
  28. 28.Best estimate of 67 × 28? (a) 2100 (b) 210 (c) 21000
  29. 29.Best estimate of 24 × 63? (a) 12000 (b) 120 (c) 1200
  30. 30.Best estimate of 439 + 599? (a) 1200 (b) 1000 (c) 800
  31. 31.Best estimate of 47 × 97? (a) 5000 (b) 500 (c) 50000
  32. 32.Best estimate of 77 × 16? (a) 16000 (b) 1600 (c) 160
  33. 33.Best estimate of 72 × 16? (a) 1400 (b) 14000 (c) 140
  34. 34.Best estimate of 66 × 32? (a) 2100 (b) 210 (c) 21000
  35. 35.Best estimate of 36 × 80? (a) 3200 (b) 32000 (c) 320
  36. 36.Best estimate of 98 × 47? (a) 50000 (b) 500 (c) 5000
  37. 37.Best estimate of 806 + 731? (a) 1700 (b) 1300 (c) 1500
  38. 38.Best estimate of 69 × 74? (a) 49000 (b) 490 (c) 4900
  39. 39.Best estimate of 38 × 92? (a) 3600 (b) 36000 (c) 360
  40. 40.Best estimate of 54 × 26? (a) 1500 (b) 15000 (c) 150

Answer key

  1. 1200
  2. 700
  3. 1500
  4. 3600
  5. 1600
  6. 3000
  7. 600
  8. 5000
  9. 600
  10. 1800
  11. 1800
  12. 1200
  13. 1100
  14. 7200
  15. 1100
  16. 600
  17. 1400
  18. 800
  19. 8100
  20. 1100
  21. 8000
  22. 1500
  23. 4200
  24. 500
  25. 1200
  26. 800
  27. 1500
  28. 2100
  29. 1200
  30. 1000
  31. 5000
  32. 1600
  33. 1400
  34. 2100
  35. 3200
  36. 5000
  37. 1500
  38. 4900
  39. 3600
  40. 1500

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