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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 275 · 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 + 2 + 3 + … + 34 =
  2. 2.1 + 2 + 3 + … + 49 =
  3. 3.1 + 2 + 3 + … + 48 =
  4. 4.1 + 2 + 3 + … + 91 =
  5. 5.1 + 2 + 3 + … + 38 =
  6. 6.1 + 2 + 3 + … + 68 =
  7. 7.1 + 2 + 3 + … + 20 =
  8. 8.1 + 2 + 3 + … + 69 =
  9. 9.1 + 3 + 5 + … + 35 =
  10. 10.1 + 2 + 3 + … + 83 =
  11. 11.1 + 2 + 3 + … + 12 =
  12. 12.1 + 2 + 3 + … + 19 =
  13. 13.1 + 2 + 3 + … + 13 =
  14. 14.1 + 3 + 5 + … + 11 =
  15. 15.1 + 2 + 3 + … + 57 =
  16. 16.1 + 2 + 3 + … + 78 =
  17. 17.1 + 2 + 3 + … + 89 =
  18. 18.1 + 2 + 3 + … + 90 =
  19. 19.1 + 3 + 5 + … + 39 =
  20. 20.1 + 2 + 3 + … + 73 =
  21. 21.1 + 3 + 5 + … + 33 =
  22. 22.1 + 2 + 3 + … + 10 =
  23. 23.1 + 2 + 3 + … + 97 =
  24. 24.1 + 2 + 3 + … + 15 =
  25. 25.1 + 2 + 3 + … + 79 =
  26. 26.1 + 2 + 3 + … + 11 =
  27. 27.1 + 2 + 3 + … + 17 =
  28. 28.1 + 3 + 5 + … + 15 =
  29. 29.1 + 2 + 3 + … + 59 =
  30. 30.1 + 2 + 3 + … + 22 =
  31. 31.1 + 2 + 3 + … + 58 =
  32. 32.1 + 2 + 3 + … + 82 =
  33. 33.1 + 3 + 5 + … + 21 =
  34. 34.1 + 2 + 3 + … + 9 =
  35. 35.1 + 2 + 3 + … + 94 =
  36. 36.1 + 2 + 3 + … + 76 =
  37. 37.1 + 2 + 3 + … + 62 =
  38. 38.1 + 2 + 3 + … + 21 =
  39. 39.1 + 3 + 5 + … + 9 =
  40. 40.1 + 3 + 5 + … + 45 =

Answer key

  1. 595
  2. 1225
  3. 1176
  4. 4186
  5. 741
  6. 2346
  7. 210
  8. 2415
  9. 324
  10. 3486
  11. 78
  12. 190
  13. 91
  14. 36
  15. 1653
  16. 3081
  17. 4005
  18. 4095
  19. 400
  20. 2701
  21. 289
  22. 55
  23. 4753
  24. 120
  25. 3160
  26. 66
  27. 153
  28. 64
  29. 1770
  30. 253
  31. 1711
  32. 3403
  33. 121
  34. 45
  35. 4465
  36. 2926
  37. 1953
  38. 231
  39. 25
  40. 529

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