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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 505 · 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 94 × 26? (a) 270 (b) 27000 (c) 2700
  2. 2.Best estimate of 40 × 71? (a) 28000 (b) 280 (c) 2800
  3. 3.Best estimate of 619 + 636? (a) 1000 (b) 1400 (c) 1200
  4. 4.Best estimate of 878 + 661? (a) 1800 (b) 1600 (c) 1400
  5. 5.Best estimate of 86 × 18? (a) 180 (b) 18000 (c) 1800
  6. 6.Best estimate of 781 + 577? (a) 1400 (b) 1200 (c) 1600
  7. 7.Best estimate of 24 × 76? (a) 1600 (b) 160 (c) 16000
  8. 8.Best estimate of 202 + 872? (a) 1300 (b) 900 (c) 1100
  9. 9.Best estimate of 644 + 349? (a) 1100 (b) 900 (c) 700
  10. 10.Best estimate of 276 + 222? (a) 500 (b) 700 (c) 300
  11. 11.Best estimate of 90 × 27? (a) 27000 (b) 2700 (c) 270
  12. 12.Best estimate of 23 × 77? (a) 1600 (b) 16000 (c) 160
  13. 13.Best estimate of 96 × 70? (a) 70000 (b) 7000 (c) 700
  14. 14.Best estimate of 399 + 409? (a) 600 (b) 800 (c) 1000
  15. 15.Best estimate of 68 × 20? (a) 140 (b) 1400 (c) 14000
  16. 16.Best estimate of 31 × 89? (a) 2700 (b) 270 (c) 27000
  17. 17.Best estimate of 430 + 804? (a) 1400 (b) 1200 (c) 1000
  18. 18.Best estimate of 821 + 826? (a) 1400 (b) 1800 (c) 1600
  19. 19.Best estimate of 361 + 266? (a) 500 (b) 900 (c) 700
  20. 20.Best estimate of 49 × 97? (a) 5000 (b) 50000 (c) 500
  21. 21.Best estimate of 56 × 43? (a) 24000 (b) 2400 (c) 240
  22. 22.Best estimate of 641 + 780? (a) 1400 (b) 1600 (c) 1200
  23. 23.Best estimate of 93 × 86? (a) 81000 (b) 8100 (c) 810
  24. 24.Best estimate of 14 × 83? (a) 800 (b) 80 (c) 8000
  25. 25.Best estimate of 46 × 64? (a) 3000 (b) 30000 (c) 300
  26. 26.Best estimate of 27 × 50? (a) 15000 (b) 1500 (c) 150
  27. 27.Best estimate of 307 + 257? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 866 + 451? (a) 1400 (b) 1600 (c) 1200
  29. 29.Best estimate of 524 + 792? (a) 1300 (b) 1100 (c) 1500
  30. 30.Best estimate of 40 × 69? (a) 28000 (b) 2800 (c) 280
  31. 31.Best estimate of 339 + 131? (a) 200 (b) 400 (c) 600
  32. 32.Best estimate of 53 × 69? (a) 350 (b) 35000 (c) 3500
  33. 33.Best estimate of 62 × 60? (a) 3600 (b) 36000 (c) 360
  34. 34.Best estimate of 60 × 66? (a) 420 (b) 42000 (c) 4200
  35. 35.Best estimate of 336 + 789? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 580 + 603? (a) 1400 (b) 1000 (c) 1200
  37. 37.Best estimate of 16 × 60? (a) 120 (b) 1200 (c) 12000
  38. 38.Best estimate of 17 × 44? (a) 800 (b) 8000 (c) 80
  39. 39.Best estimate of 60 × 83? (a) 4800 (b) 48000 (c) 480
  40. 40.Best estimate of 69 × 46? (a) 35000 (b) 350 (c) 3500

Answer key

  1. 2700
  2. 2800
  3. 1200
  4. 1600
  5. 1800
  6. 1400
  7. 1600
  8. 1100
  9. 900
  10. 500
  11. 2700
  12. 1600
  13. 7000
  14. 800
  15. 1400
  16. 2700
  17. 1200
  18. 1600
  19. 700
  20. 5000
  21. 2400
  22. 1400
  23. 8100
  24. 800
  25. 3000
  26. 1500
  27. 600
  28. 1400
  29. 1300
  30. 2800
  31. 400
  32. 3500
  33. 3600
  34. 4200
  35. 1100
  36. 1200
  37. 1200
  38. 800
  39. 4800
  40. 3500

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