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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 539 · 40 questions
TalentJR

The trick (Pairs): Pair the first and last numbers: each pair adds to n + 1. Count the pairs — or multiply n × (n + 1) and halve it. Odd numbers 1 + 3 + 5 + …: count them and multiply that count by itself.

NameDateTime takenScore ___ / 40
  1. 1.1 + 3 + 5 + … + 41 =
  2. 2.1 + 2 + 3 + … + 73 =
  3. 3.1 + 2 + 3 + … + 69 =
  4. 4.1 + 2 + 3 + … + 82 =
  5. 5.1 + 2 + 3 + … + 58 =
  6. 6.1 + 2 + 3 + … + 40 =
  7. 7.1 + 2 + 3 + … + 23 =
  8. 8.1 + 2 + 3 + … + 11 =
  9. 9.1 + 2 + 3 + … + 24 =
  10. 10.1 + 2 + 3 + … + 50 =
  11. 11.1 + 3 + 5 + … + 29 =
  12. 12.1 + 2 + 3 + … + 91 =
  13. 13.1 + 2 + 3 + … + 60 =
  14. 14.1 + 3 + 5 + … + 43 =
  15. 15.1 + 2 + 3 + … + 63 =
  16. 16.1 + 2 + 3 + … + 12 =
  17. 17.1 + 2 + 3 + … + 84 =
  18. 18.1 + 2 + 3 + … + 44 =
  19. 19.1 + 2 + 3 + … + 90 =
  20. 20.1 + 2 + 3 + … + 99 =
  21. 21.1 + 2 + 3 + … + 51 =
  22. 22.1 + 2 + 3 + … + 30 =
  23. 23.1 + 3 + 5 + … + 39 =
  24. 24.1 + 2 + 3 + … + 62 =
  25. 25.1 + 2 + 3 + … + 43 =
  26. 26.1 + 2 + 3 + … + 29 =
  27. 27.1 + 3 + 5 + … + 33 =
  28. 28.1 + 2 + 3 + … + 32 =
  29. 29.1 + 2 + 3 + … + 79 =
  30. 30.1 + 2 + 3 + … + 75 =
  31. 31.1 + 2 + 3 + … + 96 =
  32. 32.1 + 2 + 3 + … + 83 =
  33. 33.1 + 2 + 3 + … + 16 =
  34. 34.1 + 2 + 3 + … + 7 =
  35. 35.1 + 3 + 5 + … + 31 =
  36. 36.1 + 3 + 5 + … + 9 =
  37. 37.1 + 2 + 3 + … + 18 =
  38. 38.1 + 3 + 5 + … + 23 =
  39. 39.1 + 2 + 3 + … + 47 =
  40. 40.1 + 2 + 3 + … + 100 =

Answer key

  1. 441
  2. 2701
  3. 2415
  4. 3403
  5. 1711
  6. 820
  7. 276
  8. 66
  9. 300
  10. 1275
  11. 225
  12. 4186
  13. 1830
  14. 484
  15. 2016
  16. 78
  17. 3570
  18. 990
  19. 4095
  20. 4950
  21. 1326
  22. 465
  23. 400
  24. 1953
  25. 946
  26. 435
  27. 289
  28. 528
  29. 3160
  30. 2850
  31. 4656
  32. 3486
  33. 136
  34. 28
  35. 256
  36. 25
  37. 171
  38. 144
  39. 1128
  40. 5050

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