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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 771 · 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 98 × 84? (a) 800 (b) 8000 (c) 80000
  2. 2.Best estimate of 30 × 86? (a) 2700 (b) 27000 (c) 270
  3. 3.Best estimate of 26 × 29? (a) 90 (b) 900 (c) 9000
  4. 4.Best estimate of 84 × 42? (a) 320 (b) 3200 (c) 32000
  5. 5.Best estimate of 52 × 62? (a) 30000 (b) 300 (c) 3000
  6. 6.Best estimate of 76 × 23? (a) 16000 (b) 160 (c) 1600
  7. 7.Best estimate of 214 + 381? (a) 800 (b) 400 (c) 600
  8. 8.Best estimate of 852 + 745? (a) 1800 (b) 1400 (c) 1600
  9. 9.Best estimate of 90 × 76? (a) 72000 (b) 7200 (c) 720
  10. 10.Best estimate of 381 + 443? (a) 600 (b) 1000 (c) 800
  11. 11.Best estimate of 82 × 13? (a) 8000 (b) 800 (c) 80
  12. 12.Best estimate of 46 × 12? (a) 500 (b) 5000 (c) 50
  13. 13.Best estimate of 34 × 37? (a) 1200 (b) 12000 (c) 120
  14. 14.Best estimate of 16 × 98? (a) 2000 (b) 200 (c) 20000
  15. 15.Best estimate of 38 × 93? (a) 360 (b) 36000 (c) 3600
  16. 16.Best estimate of 41 × 76? (a) 320 (b) 32000 (c) 3200
  17. 17.Best estimate of 165 + 499? (a) 900 (b) 700 (c) 500
  18. 18.Best estimate of 41 × 12? (a) 4000 (b) 400 (c) 40
  19. 19.Best estimate of 30 × 36? (a) 120 (b) 1200 (c) 12000
  20. 20.Best estimate of 326 + 695? (a) 1000 (b) 800 (c) 1200
  21. 21.Best estimate of 96 × 97? (a) 100000 (b) 10000 (c) 1000
  22. 22.Best estimate of 712 + 264? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 51 × 40? (a) 20000 (b) 2000 (c) 200
  24. 24.Best estimate of 413 + 429? (a) 600 (b) 800 (c) 1000
  25. 25.Best estimate of 22 × 98? (a) 2000 (b) 200 (c) 20000
  26. 26.Best estimate of 17 × 80? (a) 160 (b) 1600 (c) 16000
  27. 27.Best estimate of 98 × 27? (a) 3000 (b) 30000 (c) 300
  28. 28.Best estimate of 790 + 205? (a) 800 (b) 1200 (c) 1000
  29. 29.Best estimate of 835 + 871? (a) 1900 (b) 1500 (c) 1700
  30. 30.Best estimate of 201 + 222? (a) 600 (b) 200 (c) 400
  31. 31.Best estimate of 26 × 37? (a) 1200 (b) 120 (c) 12000
  32. 32.Best estimate of 70 × 97? (a) 7000 (b) 70000 (c) 700
  33. 33.Best estimate of 120 + 682? (a) 600 (b) 800 (c) 1000
  34. 34.Best estimate of 492 + 419? (a) 1100 (b) 700 (c) 900
  35. 35.Best estimate of 243 + 435? (a) 600 (b) 400 (c) 800
  36. 36.Best estimate of 388 + 297? (a) 900 (b) 500 (c) 700
  37. 37.Best estimate of 67 × 17? (a) 140 (b) 14000 (c) 1400
  38. 38.Best estimate of 306 + 158? (a) 700 (b) 300 (c) 500
  39. 39.Best estimate of 36 × 13? (a) 400 (b) 4000 (c) 40
  40. 40.Best estimate of 82 × 14? (a) 800 (b) 80 (c) 8000

Answer key

  1. 8000
  2. 2700
  3. 900
  4. 3200
  5. 3000
  6. 1600
  7. 600
  8. 1600
  9. 7200
  10. 800
  11. 800
  12. 500
  13. 1200
  14. 2000
  15. 3600
  16. 3200
  17. 700
  18. 400
  19. 1200
  20. 1000
  21. 10000
  22. 1000
  23. 2000
  24. 800
  25. 2000
  26. 1600
  27. 3000
  28. 1000
  29. 1700
  30. 400
  31. 1200
  32. 7000
  33. 800
  34. 900
  35. 600
  36. 700
  37. 1400
  38. 500
  39. 400
  40. 800

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