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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 647 · 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 + … + 29 =
  2. 2.1 + 2 + 3 + … + 42 =
  3. 3.1 + 3 + 5 + … + 27 =
  4. 4.1 + 3 + 5 + … + 17 =
  5. 5.1 + 3 + 5 + … + 9 =
  6. 6.1 + 2 + 3 + … + 37 =
  7. 7.1 + 3 + 5 + … + 41 =
  8. 8.1 + 2 + 3 + … + 74 =
  9. 9.1 + 3 + 5 + … + 25 =
  10. 10.1 + 2 + 3 + … + 63 =
  11. 11.1 + 2 + 3 + … + 82 =
  12. 12.1 + 3 + 5 + … + 11 =
  13. 13.1 + 2 + 3 + … + 16 =
  14. 14.1 + 2 + 3 + … + 62 =
  15. 15.1 + 2 + 3 + … + 46 =
  16. 16.1 + 2 + 3 + … + 9 =
  17. 17.1 + 2 + 3 + … + 19 =
  18. 18.1 + 3 + 5 + … + 19 =
  19. 19.1 + 3 + 5 + … + 35 =
  20. 20.1 + 2 + 3 + … + 89 =
  21. 21.1 + 2 + 3 + … + 90 =
  22. 22.1 + 2 + 3 + … + 57 =
  23. 23.1 + 2 + 3 + … + 25 =
  24. 24.1 + 2 + 3 + … + 33 =
  25. 25.1 + 2 + 3 + … + 75 =
  26. 26.1 + 2 + 3 + … + 41 =
  27. 27.1 + 2 + 3 + … + 97 =
  28. 28.1 + 2 + 3 + … + 94 =
  29. 29.1 + 2 + 3 + … + 83 =
  30. 30.1 + 3 + 5 + … + 13 =
  31. 31.1 + 3 + 5 + … + 23 =
  32. 32.1 + 2 + 3 + … + 26 =
  33. 33.1 + 2 + 3 + … + 51 =
  34. 34.1 + 2 + 3 + … + 69 =
  35. 35.1 + 2 + 3 + … + 87 =
  36. 36.1 + 3 + 5 + … + 37 =
  37. 37.1 + 2 + 3 + … + 40 =
  38. 38.1 + 2 + 3 + … + 76 =
  39. 39.1 + 2 + 3 + … + 68 =
  40. 40.1 + 2 + 3 + … + 55 =

Answer key

  1. 435
  2. 903
  3. 196
  4. 81
  5. 25
  6. 703
  7. 441
  8. 2775
  9. 169
  10. 2016
  11. 3403
  12. 36
  13. 136
  14. 1953
  15. 1081
  16. 45
  17. 190
  18. 100
  19. 324
  20. 4005
  21. 4095
  22. 1653
  23. 325
  24. 561
  25. 2850
  26. 861
  27. 4753
  28. 4465
  29. 3486
  30. 49
  31. 144
  32. 351
  33. 1326
  34. 2415
  35. 3828
  36. 361
  37. 820
  38. 2926
  39. 2346
  40. 1540

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