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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 317 · 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 + … + 26 =
  2. 2.1 + 3 + 5 + … + 17 =
  3. 3.1 + 3 + 5 + … + 15 =
  4. 4.1 + 3 + 5 + … + 19 =
  5. 5.1 + 2 + 3 + … + 87 =
  6. 6.1 + 2 + 3 + … + 73 =
  7. 7.1 + 2 + 3 + … + 23 =
  8. 8.1 + 2 + 3 + … + 43 =
  9. 9.1 + 2 + 3 + … + 41 =
  10. 10.1 + 2 + 3 + … + 100 =
  11. 11.1 + 2 + 3 + … + 97 =
  12. 12.1 + 2 + 3 + … + 61 =
  13. 13.1 + 3 + 5 + … + 41 =
  14. 14.1 + 2 + 3 + … + 82 =
  15. 15.1 + 2 + 3 + … + 95 =
  16. 16.1 + 2 + 3 + … + 8 =
  17. 17.1 + 2 + 3 + … + 33 =
  18. 18.1 + 2 + 3 + … + 9 =
  19. 19.1 + 3 + 5 + … + 25 =
  20. 20.1 + 2 + 3 + … + 63 =
  21. 21.1 + 2 + 3 + … + 99 =
  22. 22.1 + 3 + 5 + … + 23 =
  23. 23.1 + 3 + 5 + … + 11 =
  24. 24.1 + 2 + 3 + … + 72 =
  25. 25.1 + 2 + 3 + … + 12 =
  26. 26.1 + 2 + 3 + … + 89 =
  27. 27.1 + 3 + 5 + … + 49 =
  28. 28.1 + 3 + 5 + … + 29 =
  29. 29.1 + 2 + 3 + … + 51 =
  30. 30.1 + 3 + 5 + … + 9 =
  31. 31.1 + 2 + 3 + … + 98 =
  32. 32.1 + 2 + 3 + … + 96 =
  33. 33.1 + 3 + 5 + … + 43 =
  34. 34.1 + 2 + 3 + … + 11 =
  35. 35.1 + 2 + 3 + … + 79 =
  36. 36.1 + 3 + 5 + … + 13 =
  37. 37.1 + 2 + 3 + … + 55 =
  38. 38.1 + 2 + 3 + … + 47 =
  39. 39.1 + 2 + 3 + … + 91 =
  40. 40.1 + 2 + 3 + … + 84 =

Answer key

  1. 351
  2. 81
  3. 64
  4. 100
  5. 3828
  6. 2701
  7. 276
  8. 946
  9. 861
  10. 5050
  11. 4753
  12. 1891
  13. 441
  14. 3403
  15. 4560
  16. 36
  17. 561
  18. 45
  19. 169
  20. 2016
  21. 4950
  22. 144
  23. 36
  24. 2628
  25. 78
  26. 4005
  27. 625
  28. 225
  29. 1326
  30. 25
  31. 4851
  32. 4656
  33. 484
  34. 66
  35. 3160
  36. 49
  37. 1540
  38. 1128
  39. 4186
  40. 3570

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