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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 901 · 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 + … + 8 =
  2. 2.1 + 3 + 5 + … + 43 =
  3. 3.1 + 2 + 3 + … + 44 =
  4. 4.1 + 2 + 3 + … + 39 =
  5. 5.1 + 2 + 3 + … + 85 =
  6. 6.1 + 3 + 5 + … + 19 =
  7. 7.1 + 3 + 5 + … + 27 =
  8. 8.1 + 2 + 3 + … + 36 =
  9. 9.1 + 3 + 5 + … + 11 =
  10. 10.1 + 3 + 5 + … + 21 =
  11. 11.1 + 2 + 3 + … + 60 =
  12. 12.1 + 2 + 3 + … + 89 =
  13. 13.1 + 2 + 3 + … + 94 =
  14. 14.1 + 2 + 3 + … + 80 =
  15. 15.1 + 2 + 3 + … + 9 =
  16. 16.1 + 3 + 5 + … + 23 =
  17. 17.1 + 3 + 5 + … + 45 =
  18. 18.1 + 2 + 3 + … + 49 =
  19. 19.1 + 2 + 3 + … + 24 =
  20. 20.1 + 2 + 3 + … + 28 =
  21. 21.1 + 2 + 3 + … + 14 =
  22. 22.1 + 2 + 3 + … + 82 =
  23. 23.1 + 3 + 5 + … + 39 =
  24. 24.1 + 3 + 5 + … + 37 =
  25. 25.1 + 2 + 3 + … + 18 =
  26. 26.1 + 2 + 3 + … + 7 =
  27. 27.1 + 2 + 3 + … + 11 =
  28. 28.1 + 3 + 5 + … + 13 =
  29. 29.1 + 3 + 5 + … + 35 =
  30. 30.1 + 2 + 3 + … + 64 =
  31. 31.1 + 3 + 5 + … + 29 =
  32. 32.1 + 2 + 3 + … + 59 =
  33. 33.1 + 2 + 3 + … + 98 =
  34. 34.1 + 2 + 3 + … + 61 =
  35. 35.1 + 2 + 3 + … + 68 =
  36. 36.1 + 2 + 3 + … + 97 =
  37. 37.1 + 2 + 3 + … + 67 =
  38. 38.1 + 2 + 3 + … + 16 =
  39. 39.1 + 2 + 3 + … + 57 =
  40. 40.1 + 2 + 3 + … + 43 =

Answer key

  1. 36
  2. 484
  3. 990
  4. 780
  5. 3655
  6. 100
  7. 196
  8. 666
  9. 36
  10. 121
  11. 1830
  12. 4005
  13. 4465
  14. 3240
  15. 45
  16. 144
  17. 529
  18. 1225
  19. 300
  20. 406
  21. 105
  22. 3403
  23. 400
  24. 361
  25. 171
  26. 28
  27. 66
  28. 49
  29. 324
  30. 2080
  31. 225
  32. 1770
  33. 4851
  34. 1891
  35. 2346
  36. 4753
  37. 2278
  38. 136
  39. 1653
  40. 946

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