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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 320 · 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 288 + 456? (a) 1000 (b) 800 (c) 600
  2. 2.Best estimate of 158 + 820? (a) 800 (b) 1200 (c) 1000
  3. 3.Best estimate of 20 × 83? (a) 1600 (b) 160 (c) 16000
  4. 4.Best estimate of 74 × 39? (a) 28000 (b) 280 (c) 2800
  5. 5.Best estimate of 244 + 382? (a) 800 (b) 600 (c) 400
  6. 6.Best estimate of 33 × 59? (a) 18000 (b) 1800 (c) 180
  7. 7.Best estimate of 809 + 276? (a) 1300 (b) 900 (c) 1100
  8. 8.Best estimate of 94 × 51? (a) 450 (b) 45000 (c) 4500
  9. 9.Best estimate of 813 + 231? (a) 1200 (b) 1000 (c) 800
  10. 10.Best estimate of 26 × 86? (a) 27000 (b) 270 (c) 2700
  11. 11.Best estimate of 828 + 155? (a) 1000 (b) 1200 (c) 800
  12. 12.Best estimate of 139 + 495? (a) 600 (b) 800 (c) 400
  13. 13.Best estimate of 243 + 488? (a) 700 (b) 900 (c) 500
  14. 14.Best estimate of 93 × 42? (a) 3600 (b) 360 (c) 36000
  15. 15.Best estimate of 36 × 97? (a) 400 (b) 4000 (c) 40000
  16. 16.Best estimate of 26 × 96? (a) 300 (b) 30000 (c) 3000
  17. 17.Best estimate of 32 × 76? (a) 24000 (b) 240 (c) 2400
  18. 18.Best estimate of 774 + 694? (a) 1300 (b) 1700 (c) 1500
  19. 19.Best estimate of 573 + 275? (a) 1100 (b) 700 (c) 900
  20. 20.Best estimate of 44 × 16? (a) 8000 (b) 800 (c) 80
  21. 21.Best estimate of 16 × 54? (a) 1000 (b) 10000 (c) 100
  22. 22.Best estimate of 72 × 59? (a) 420 (b) 42000 (c) 4200
  23. 23.Best estimate of 409 + 606? (a) 800 (b) 1000 (c) 1200
  24. 24.Best estimate of 16 × 69? (a) 140 (b) 1400 (c) 14000
  25. 25.Best estimate of 94 × 58? (a) 5400 (b) 540 (c) 54000
  26. 26.Best estimate of 43 × 44? (a) 160 (b) 1600 (c) 16000
  27. 27.Best estimate of 771 + 369? (a) 1200 (b) 1000 (c) 1400
  28. 28.Best estimate of 262 + 573? (a) 1100 (b) 900 (c) 700
  29. 29.Best estimate of 854 + 393? (a) 1300 (b) 1500 (c) 1100
  30. 30.Best estimate of 814 + 275? (a) 1100 (b) 1300 (c) 900
  31. 31.Best estimate of 41 × 66? (a) 280 (b) 28000 (c) 2800
  32. 32.Best estimate of 21 × 33? (a) 600 (b) 6000 (c) 60
  33. 33.Best estimate of 19 × 54? (a) 100 (b) 10000 (c) 1000
  34. 34.Best estimate of 86 × 43? (a) 36000 (b) 360 (c) 3600
  35. 35.Best estimate of 727 + 572? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 48 × 36? (a) 20000 (b) 2000 (c) 200
  37. 37.Best estimate of 204 + 306? (a) 700 (b) 500 (c) 300
  38. 38.Best estimate of 544 + 454? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 42 × 16? (a) 80 (b) 800 (c) 8000
  40. 40.Best estimate of 76 × 31? (a) 2400 (b) 240 (c) 24000

Answer key

  1. 800
  2. 1000
  3. 1600
  4. 2800
  5. 600
  6. 1800
  7. 1100
  8. 4500
  9. 1000
  10. 2700
  11. 1000
  12. 600
  13. 700
  14. 3600
  15. 4000
  16. 3000
  17. 2400
  18. 1500
  19. 900
  20. 800
  21. 1000
  22. 4200
  23. 1000
  24. 1400
  25. 5400
  26. 1600
  27. 1200
  28. 900
  29. 1300
  30. 1100
  31. 2800
  32. 600
  33. 1000
  34. 3600
  35. 1300
  36. 2000
  37. 500
  38. 1000
  39. 800
  40. 2400

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