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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 226 · 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 238 + 383? (a) 400 (b) 800 (c) 600
  2. 2.Best estimate of 86 × 58? (a) 5400 (b) 54000 (c) 540
  3. 3.Best estimate of 297 + 825? (a) 900 (b) 1300 (c) 1100
  4. 4.Best estimate of 34 × 63? (a) 180 (b) 18000 (c) 1800
  5. 5.Best estimate of 484 + 244? (a) 900 (b) 500 (c) 700
  6. 6.Best estimate of 80 × 28? (a) 24000 (b) 240 (c) 2400
  7. 7.Best estimate of 46 × 32? (a) 15000 (b) 150 (c) 1500
  8. 8.Best estimate of 40 × 96? (a) 4000 (b) 40000 (c) 400
  9. 9.Best estimate of 91 × 83? (a) 720 (b) 72000 (c) 7200
  10. 10.Best estimate of 661 + 215? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 282 + 466? (a) 800 (b) 600 (c) 1000
  12. 12.Best estimate of 17 × 79? (a) 160 (b) 16000 (c) 1600
  13. 13.Best estimate of 461 + 200? (a) 900 (b) 500 (c) 700
  14. 14.Best estimate of 222 + 562? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 91 × 14? (a) 9000 (b) 900 (c) 90
  16. 16.Best estimate of 553 + 427? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 774 + 305? (a) 1100 (b) 900 (c) 1300
  18. 18.Best estimate of 32 × 26? (a) 900 (b) 90 (c) 9000
  19. 19.Best estimate of 19 × 79? (a) 160 (b) 16000 (c) 1600
  20. 20.Best estimate of 307 + 137? (a) 400 (b) 600 (c) 200
  21. 21.Best estimate of 711 + 411? (a) 900 (b) 1300 (c) 1100
  22. 22.Best estimate of 137 + 247? (a) 500 (b) 100 (c) 300
  23. 23.Best estimate of 167 + 363? (a) 400 (b) 600 (c) 800
  24. 24.Best estimate of 49 × 96? (a) 5000 (b) 500 (c) 50000
  25. 25.Best estimate of 88 × 12? (a) 900 (b) 90 (c) 9000
  26. 26.Best estimate of 443 + 444? (a) 600 (b) 800 (c) 1000
  27. 27.Best estimate of 19 × 73? (a) 14000 (b) 1400 (c) 140
  28. 28.Best estimate of 333 + 696? (a) 1000 (b) 800 (c) 1200
  29. 29.Best estimate of 61 × 56? (a) 3600 (b) 36000 (c) 360
  30. 30.Best estimate of 54 × 32? (a) 15000 (b) 1500 (c) 150
  31. 31.Best estimate of 675 + 152? (a) 900 (b) 1100 (c) 700
  32. 32.Best estimate of 30 × 41? (a) 120 (b) 1200 (c) 12000
  33. 33.Best estimate of 859 + 538? (a) 1400 (b) 1200 (c) 1600
  34. 34.Best estimate of 781 + 528? (a) 1300 (b) 1100 (c) 1500
  35. 35.Best estimate of 46 × 17? (a) 100 (b) 10000 (c) 1000
  36. 36.Best estimate of 51 × 96? (a) 500 (b) 50000 (c) 5000
  37. 37.Best estimate of 219 + 310? (a) 300 (b) 700 (c) 500
  38. 38.Best estimate of 145 + 398? (a) 700 (b) 300 (c) 500
  39. 39.Best estimate of 91 × 76? (a) 7200 (b) 72000 (c) 720
  40. 40.Best estimate of 854 + 195? (a) 1300 (b) 900 (c) 1100

Answer key

  1. 600
  2. 5400
  3. 1100
  4. 1800
  5. 700
  6. 2400
  7. 1500
  8. 4000
  9. 7200
  10. 900
  11. 800
  12. 1600
  13. 700
  14. 800
  15. 900
  16. 1000
  17. 1100
  18. 900
  19. 1600
  20. 400
  21. 1100
  22. 300
  23. 600
  24. 5000
  25. 900
  26. 800
  27. 1400
  28. 1000
  29. 3600
  30. 1500
  31. 900
  32. 1200
  33. 1400
  34. 1300
  35. 1000
  36. 5000
  37. 500
  38. 500
  39. 7200
  40. 1100

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