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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 339 · 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 539 + 261? (a) 1000 (b) 600 (c) 800
  2. 2.Best estimate of 359 + 805? (a) 1200 (b) 1000 (c) 1400
  3. 3.Best estimate of 542 + 308? (a) 600 (b) 1000 (c) 800
  4. 4.Best estimate of 41 × 92? (a) 360 (b) 3600 (c) 36000
  5. 5.Best estimate of 34 × 26? (a) 9000 (b) 900 (c) 90
  6. 6.Best estimate of 251 + 306? (a) 600 (b) 800 (c) 400
  7. 7.Best estimate of 213 + 206? (a) 600 (b) 400 (c) 200
  8. 8.Best estimate of 76 × 83? (a) 64000 (b) 6400 (c) 640
  9. 9.Best estimate of 203 + 189? (a) 200 (b) 400 (c) 600
  10. 10.Best estimate of 191 + 122? (a) 300 (b) 100 (c) 500
  11. 11.Best estimate of 27 × 26? (a) 90 (b) 900 (c) 9000
  12. 12.Best estimate of 783 + 365? (a) 1000 (b) 1400 (c) 1200
  13. 13.Best estimate of 358 + 222? (a) 800 (b) 400 (c) 600
  14. 14.Best estimate of 819 + 372? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 50 × 97? (a) 500 (b) 5000 (c) 50000
  16. 16.Best estimate of 659 + 709? (a) 1400 (b) 1200 (c) 1600
  17. 17.Best estimate of 183 + 251? (a) 500 (b) 300 (c) 700
  18. 18.Best estimate of 96 × 84? (a) 80000 (b) 8000 (c) 800
  19. 19.Best estimate of 18 × 46? (a) 10000 (b) 1000 (c) 100
  20. 20.Best estimate of 308 + 183? (a) 500 (b) 300 (c) 700
  21. 21.Best estimate of 13 × 84? (a) 80 (b) 800 (c) 8000
  22. 22.Best estimate of 701 + 597? (a) 1100 (b) 1500 (c) 1300
  23. 23.Best estimate of 14 × 46? (a) 5000 (b) 500 (c) 50
  24. 24.Best estimate of 276 + 136? (a) 400 (b) 200 (c) 600
  25. 25.Best estimate of 31 × 42? (a) 1200 (b) 12000 (c) 120
  26. 26.Best estimate of 62 × 49? (a) 30000 (b) 3000 (c) 300
  27. 27.Best estimate of 200 + 713? (a) 900 (b) 700 (c) 1100
  28. 28.Best estimate of 34 × 82? (a) 240 (b) 24000 (c) 2400
  29. 29.Best estimate of 79 × 87? (a) 72000 (b) 7200 (c) 720
  30. 30.Best estimate of 814 + 285? (a) 900 (b) 1100 (c) 1300
  31. 31.Best estimate of 87 × 36? (a) 3600 (b) 36000 (c) 360
  32. 32.Best estimate of 41 × 98? (a) 400 (b) 4000 (c) 40000
  33. 33.Best estimate of 13 × 79? (a) 800 (b) 8000 (c) 80
  34. 34.Best estimate of 366 + 164? (a) 800 (b) 600 (c) 400
  35. 35.Best estimate of 46 × 94? (a) 450 (b) 45000 (c) 4500
  36. 36.Best estimate of 32 × 67? (a) 210 (b) 21000 (c) 2100
  37. 37.Best estimate of 44 × 28? (a) 120 (b) 1200 (c) 12000
  38. 38.Best estimate of 56 × 82? (a) 480 (b) 48000 (c) 4800
  39. 39.Best estimate of 187 + 280? (a) 300 (b) 500 (c) 700
  40. 40.Best estimate of 63 × 90? (a) 5400 (b) 540 (c) 54000

Answer key

  1. 800
  2. 1200
  3. 800
  4. 3600
  5. 900
  6. 600
  7. 400
  8. 6400
  9. 400
  10. 300
  11. 900
  12. 1200
  13. 600
  14. 1200
  15. 5000
  16. 1400
  17. 500
  18. 8000
  19. 1000
  20. 500
  21. 800
  22. 1300
  23. 500
  24. 400
  25. 1200
  26. 3000
  27. 900
  28. 2400
  29. 7200
  30. 1100
  31. 3600
  32. 4000
  33. 800
  34. 600
  35. 4500
  36. 2100
  37. 1200
  38. 4800
  39. 500
  40. 5400

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