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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 979 · 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 + … + 15 =
  2. 2.1 + 2 + 3 + … + 32 =
  3. 3.1 + 2 + 3 + … + 57 =
  4. 4.1 + 3 + 5 + … + 47 =
  5. 5.1 + 3 + 5 + … + 21 =
  6. 6.1 + 3 + 5 + … + 17 =
  7. 7.1 + 2 + 3 + … + 76 =
  8. 8.1 + 2 + 3 + … + 85 =
  9. 9.1 + 2 + 3 + … + 80 =
  10. 10.1 + 2 + 3 + … + 16 =
  11. 11.1 + 2 + 3 + … + 38 =
  12. 12.1 + 2 + 3 + … + 48 =
  13. 13.1 + 3 + 5 + … + 43 =
  14. 14.1 + 3 + 5 + … + 23 =
  15. 15.1 + 2 + 3 + … + 30 =
  16. 16.1 + 2 + 3 + … + 100 =
  17. 17.1 + 2 + 3 + … + 91 =
  18. 18.1 + 2 + 3 + … + 78 =
  19. 19.1 + 3 + 5 + … + 41 =
  20. 20.1 + 2 + 3 + … + 77 =
  21. 21.1 + 2 + 3 + … + 99 =
  22. 22.1 + 3 + 5 + … + 19 =
  23. 23.1 + 2 + 3 + … + 87 =
  24. 24.1 + 2 + 3 + … + 43 =
  25. 25.1 + 3 + 5 + … + 11 =
  26. 26.1 + 2 + 3 + … + 58 =
  27. 27.1 + 2 + 3 + … + 9 =
  28. 28.1 + 2 + 3 + … + 84 =
  29. 29.1 + 2 + 3 + … + 49 =
  30. 30.1 + 2 + 3 + … + 47 =
  31. 31.1 + 2 + 3 + … + 92 =
  32. 32.1 + 2 + 3 + … + 73 =
  33. 33.1 + 2 + 3 + … + 26 =
  34. 34.1 + 2 + 3 + … + 51 =
  35. 35.1 + 2 + 3 + … + 96 =
  36. 36.1 + 3 + 5 + … + 33 =
  37. 37.1 + 2 + 3 + … + 62 =
  38. 38.1 + 2 + 3 + … + 68 =
  39. 39.1 + 3 + 5 + … + 39 =
  40. 40.1 + 2 + 3 + … + 23 =

Answer key

  1. 64
  2. 528
  3. 1653
  4. 576
  5. 121
  6. 81
  7. 2926
  8. 3655
  9. 3240
  10. 136
  11. 741
  12. 1176
  13. 484
  14. 144
  15. 465
  16. 5050
  17. 4186
  18. 3081
  19. 441
  20. 3003
  21. 4950
  22. 100
  23. 3828
  24. 946
  25. 36
  26. 1711
  27. 45
  28. 3570
  29. 1225
  30. 1128
  31. 4278
  32. 2701
  33. 351
  34. 1326
  35. 4656
  36. 289
  37. 1953
  38. 2346
  39. 400
  40. 276

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