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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 616 · 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 + … + 19 =
  2. 2.1 + 2 + 3 + … + 17 =
  3. 3.1 + 2 + 3 + … + 25 =
  4. 4.1 + 2 + 3 + … + 29 =
  5. 5.1 + 3 + 5 + … + 39 =
  6. 6.1 + 2 + 3 + … + 30 =
  7. 7.1 + 2 + 3 + … + 94 =
  8. 8.1 + 3 + 5 + … + 13 =
  9. 9.1 + 2 + 3 + … + 75 =
  10. 10.1 + 3 + 5 + … + 9 =
  11. 11.1 + 2 + 3 + … + 51 =
  12. 12.1 + 2 + 3 + … + 46 =
  13. 13.1 + 2 + 3 + … + 92 =
  14. 14.1 + 3 + 5 + … + 43 =
  15. 15.1 + 3 + 5 + … + 35 =
  16. 16.1 + 2 + 3 + … + 42 =
  17. 17.1 + 3 + 5 + … + 21 =
  18. 18.1 + 3 + 5 + … + 37 =
  19. 19.1 + 2 + 3 + … + 89 =
  20. 20.1 + 2 + 3 + … + 9 =
  21. 21.1 + 2 + 3 + … + 16 =
  22. 22.1 + 2 + 3 + … + 36 =
  23. 23.1 + 2 + 3 + … + 22 =
  24. 24.1 + 3 + 5 + … + 47 =
  25. 25.1 + 2 + 3 + … + 38 =
  26. 26.1 + 2 + 3 + … + 77 =
  27. 27.1 + 2 + 3 + … + 59 =
  28. 28.1 + 2 + 3 + … + 96 =
  29. 29.1 + 2 + 3 + … + 66 =
  30. 30.1 + 3 + 5 + … + 31 =
  31. 31.1 + 2 + 3 + … + 32 =
  32. 32.1 + 2 + 3 + … + 99 =
  33. 33.1 + 2 + 3 + … + 76 =
  34. 34.1 + 2 + 3 + … + 86 =
  35. 35.1 + 2 + 3 + … + 18 =
  36. 36.1 + 3 + 5 + … + 11 =
  37. 37.1 + 2 + 3 + … + 100 =
  38. 38.1 + 3 + 5 + … + 33 =
  39. 39.1 + 3 + 5 + … + 29 =
  40. 40.1 + 2 + 3 + … + 19 =

Answer key

  1. 100
  2. 153
  3. 325
  4. 435
  5. 400
  6. 465
  7. 4465
  8. 49
  9. 2850
  10. 25
  11. 1326
  12. 1081
  13. 4278
  14. 484
  15. 324
  16. 903
  17. 121
  18. 361
  19. 4005
  20. 45
  21. 136
  22. 666
  23. 253
  24. 576
  25. 741
  26. 3003
  27. 1770
  28. 4656
  29. 2211
  30. 256
  31. 528
  32. 4950
  33. 2926
  34. 3741
  35. 171
  36. 36
  37. 5050
  38. 289
  39. 225
  40. 190

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