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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 756 · 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 + … + 69 =
  2. 2.1 + 3 + 5 + … + 27 =
  3. 3.1 + 2 + 3 + … + 76 =
  4. 4.1 + 2 + 3 + … + 12 =
  5. 5.1 + 2 + 3 + … + 27 =
  6. 6.1 + 2 + 3 + … + 72 =
  7. 7.1 + 2 + 3 + … + 24 =
  8. 8.1 + 2 + 3 + … + 51 =
  9. 9.1 + 2 + 3 + … + 18 =
  10. 10.1 + 2 + 3 + … + 46 =
  11. 11.1 + 2 + 3 + … + 47 =
  12. 12.1 + 3 + 5 + … + 29 =
  13. 13.1 + 2 + 3 + … + 26 =
  14. 14.1 + 3 + 5 + … + 41 =
  15. 15.1 + 2 + 3 + … + 25 =
  16. 16.1 + 3 + 5 + … + 25 =
  17. 17.1 + 2 + 3 + … + 63 =
  18. 18.1 + 2 + 3 + … + 97 =
  19. 19.1 + 3 + 5 + … + 31 =
  20. 20.1 + 2 + 3 + … + 81 =
  21. 21.1 + 3 + 5 + … + 49 =
  22. 22.1 + 3 + 5 + … + 21 =
  23. 23.1 + 2 + 3 + … + 28 =
  24. 24.1 + 2 + 3 + … + 73 =
  25. 25.1 + 2 + 3 + … + 84 =
  26. 26.1 + 2 + 3 + … + 45 =
  27. 27.1 + 3 + 5 + … + 43 =
  28. 28.1 + 3 + 5 + … + 47 =
  29. 29.1 + 2 + 3 + … + 13 =
  30. 30.1 + 2 + 3 + … + 96 =
  31. 31.1 + 2 + 3 + … + 30 =
  32. 32.1 + 2 + 3 + … + 86 =
  33. 33.1 + 2 + 3 + … + 8 =
  34. 34.1 + 3 + 5 + … + 17 =
  35. 35.1 + 2 + 3 + … + 67 =
  36. 36.1 + 2 + 3 + … + 78 =
  37. 37.1 + 2 + 3 + … + 98 =
  38. 38.1 + 3 + 5 + … + 11 =
  39. 39.1 + 2 + 3 + … + 60 =
  40. 40.1 + 2 + 3 + … + 43 =

Answer key

  1. 2415
  2. 196
  3. 2926
  4. 78
  5. 378
  6. 2628
  7. 300
  8. 1326
  9. 171
  10. 1081
  11. 1128
  12. 225
  13. 351
  14. 441
  15. 325
  16. 169
  17. 2016
  18. 4753
  19. 256
  20. 3321
  21. 625
  22. 121
  23. 406
  24. 2701
  25. 3570
  26. 1035
  27. 484
  28. 576
  29. 91
  30. 4656
  31. 465
  32. 3741
  33. 36
  34. 81
  35. 2278
  36. 3081
  37. 4851
  38. 36
  39. 1830
  40. 946

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