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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 325 · 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 + … + 49 =
  2. 2.1 + 2 + 3 + … + 19 =
  3. 3.1 + 2 + 3 + … + 21 =
  4. 4.1 + 2 + 3 + … + 38 =
  5. 5.1 + 3 + 5 + … + 25 =
  6. 6.1 + 2 + 3 + … + 62 =
  7. 7.1 + 2 + 3 + … + 84 =
  8. 8.1 + 3 + 5 + … + 23 =
  9. 9.1 + 2 + 3 + … + 100 =
  10. 10.1 + 2 + 3 + … + 14 =
  11. 11.1 + 2 + 3 + … + 7 =
  12. 12.1 + 3 + 5 + … + 11 =
  13. 13.1 + 3 + 5 + … + 45 =
  14. 14.1 + 2 + 3 + … + 94 =
  15. 15.1 + 2 + 3 + … + 68 =
  16. 16.1 + 2 + 3 + … + 88 =
  17. 17.1 + 3 + 5 + … + 31 =
  18. 18.1 + 3 + 5 + … + 43 =
  19. 19.1 + 3 + 5 + … + 39 =
  20. 20.1 + 2 + 3 + … + 17 =
  21. 21.1 + 2 + 3 + … + 70 =
  22. 22.1 + 2 + 3 + … + 89 =
  23. 23.1 + 2 + 3 + … + 86 =
  24. 24.1 + 2 + 3 + … + 91 =
  25. 25.1 + 2 + 3 + … + 74 =
  26. 26.1 + 2 + 3 + … + 73 =
  27. 27.1 + 3 + 5 + … + 13 =
  28. 28.1 + 3 + 5 + … + 33 =
  29. 29.1 + 3 + 5 + … + 17 =
  30. 30.1 + 2 + 3 + … + 58 =
  31. 31.1 + 2 + 3 + … + 32 =
  32. 32.1 + 2 + 3 + … + 60 =
  33. 33.1 + 2 + 3 + … + 51 =
  34. 34.1 + 3 + 5 + … + 19 =
  35. 35.1 + 3 + 5 + … + 47 =
  36. 36.1 + 2 + 3 + … + 96 =
  37. 37.1 + 2 + 3 + … + 61 =
  38. 38.1 + 2 + 3 + … + 24 =
  39. 39.1 + 2 + 3 + … + 16 =
  40. 40.1 + 2 + 3 + … + 46 =

Answer key

  1. 625
  2. 190
  3. 231
  4. 741
  5. 169
  6. 1953
  7. 3570
  8. 144
  9. 5050
  10. 105
  11. 28
  12. 36
  13. 529
  14. 4465
  15. 2346
  16. 3916
  17. 256
  18. 484
  19. 400
  20. 153
  21. 2485
  22. 4005
  23. 3741
  24. 4186
  25. 2775
  26. 2701
  27. 49
  28. 289
  29. 81
  30. 1711
  31. 528
  32. 1830
  33. 1326
  34. 100
  35. 576
  36. 4656
  37. 1891
  38. 300
  39. 136
  40. 1081

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