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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 319 · 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 76 × 17? (a) 16000 (b) 1600 (c) 160
  2. 2.Best estimate of 27 × 92? (a) 27000 (b) 270 (c) 2700
  3. 3.Best estimate of 16 × 29? (a) 60 (b) 600 (c) 6000
  4. 4.Best estimate of 63 × 97? (a) 600 (b) 6000 (c) 60000
  5. 5.Best estimate of 54 × 63? (a) 3000 (b) 30000 (c) 300
  6. 6.Best estimate of 49 × 56? (a) 3000 (b) 300 (c) 30000
  7. 7.Best estimate of 27 × 12? (a) 3000 (b) 30 (c) 300
  8. 8.Best estimate of 22 × 98? (a) 2000 (b) 200 (c) 20000
  9. 9.Best estimate of 98 × 26? (a) 3000 (b) 300 (c) 30000
  10. 10.Best estimate of 721 + 712? (a) 1400 (b) 1600 (c) 1200
  11. 11.Best estimate of 33 × 96? (a) 300 (b) 3000 (c) 30000
  12. 12.Best estimate of 232 + 239? (a) 400 (b) 600 (c) 200
  13. 13.Best estimate of 409 + 169? (a) 600 (b) 800 (c) 400
  14. 14.Best estimate of 84 × 60? (a) 48000 (b) 480 (c) 4800
  15. 15.Best estimate of 36 × 94? (a) 36000 (b) 3600 (c) 360
  16. 16.Best estimate of 23 × 53? (a) 10000 (b) 100 (c) 1000
  17. 17.Best estimate of 76 × 42? (a) 320 (b) 32000 (c) 3200
  18. 18.Best estimate of 97 × 50? (a) 5000 (b) 50000 (c) 500
  19. 19.Best estimate of 58 × 60? (a) 36000 (b) 360 (c) 3600
  20. 20.Best estimate of 67 × 66? (a) 49000 (b) 4900 (c) 490
  21. 21.Best estimate of 286 + 640? (a) 700 (b) 900 (c) 1100
  22. 22.Best estimate of 455 + 621? (a) 1300 (b) 1100 (c) 900
  23. 23.Best estimate of 46 × 67? (a) 3500 (b) 35000 (c) 350
  24. 24.Best estimate of 880 + 618? (a) 1500 (b) 1300 (c) 1700
  25. 25.Best estimate of 62 × 12? (a) 600 (b) 60 (c) 6000
  26. 26.Best estimate of 142 + 256? (a) 400 (b) 600 (c) 200
  27. 27.Best estimate of 92 × 36? (a) 360 (b) 36000 (c) 3600
  28. 28.Best estimate of 31 × 36? (a) 1200 (b) 120 (c) 12000
  29. 29.Best estimate of 14 × 42? (a) 4000 (b) 40 (c) 400
  30. 30.Best estimate of 36 × 33? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 77 × 86? (a) 72000 (b) 7200 (c) 720
  32. 32.Best estimate of 331 + 728? (a) 1000 (b) 1200 (c) 800
  33. 33.Best estimate of 665 + 266? (a) 1000 (b) 1200 (c) 800
  34. 34.Best estimate of 651 + 494? (a) 1000 (b) 1200 (c) 1400
  35. 35.Best estimate of 20 × 91? (a) 1800 (b) 180 (c) 18000
  36. 36.Best estimate of 34 × 82? (a) 2400 (b) 24000 (c) 240
  37. 37.Best estimate of 800 + 393? (a) 1400 (b) 1000 (c) 1200
  38. 38.Best estimate of 84 × 12? (a) 8000 (b) 800 (c) 80
  39. 39.Best estimate of 53 × 27? (a) 150 (b) 15000 (c) 1500
  40. 40.Best estimate of 76 × 54? (a) 400 (b) 40000 (c) 4000

Answer key

  1. 1600
  2. 2700
  3. 600
  4. 6000
  5. 3000
  6. 3000
  7. 300
  8. 2000
  9. 3000
  10. 1400
  11. 3000
  12. 400
  13. 600
  14. 4800
  15. 3600
  16. 1000
  17. 3200
  18. 5000
  19. 3600
  20. 4900
  21. 900
  22. 1100
  23. 3500
  24. 1500
  25. 600
  26. 400
  27. 3600
  28. 1200
  29. 400
  30. 1200
  31. 7200
  32. 1000
  33. 1000
  34. 1200
  35. 1800
  36. 2400
  37. 1200
  38. 800
  39. 1500
  40. 4000

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