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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 306 · 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 + … + 12 =
  2. 2.1 + 3 + 5 + … + 49 =
  3. 3.1 + 3 + 5 + … + 17 =
  4. 4.1 + 3 + 5 + … + 9 =
  5. 5.1 + 2 + 3 + … + 50 =
  6. 6.1 + 3 + 5 + … + 37 =
  7. 7.1 + 2 + 3 + … + 85 =
  8. 8.1 + 2 + 3 + … + 22 =
  9. 9.1 + 2 + 3 + … + 31 =
  10. 10.1 + 3 + 5 + … + 23 =
  11. 11.1 + 2 + 3 + … + 25 =
  12. 12.1 + 2 + 3 + … + 100 =
  13. 13.1 + 3 + 5 + … + 27 =
  14. 14.1 + 2 + 3 + … + 75 =
  15. 15.1 + 2 + 3 + … + 64 =
  16. 16.1 + 2 + 3 + … + 11 =
  17. 17.1 + 3 + 5 + … + 29 =
  18. 18.1 + 2 + 3 + … + 73 =
  19. 19.1 + 2 + 3 + … + 26 =
  20. 20.1 + 2 + 3 + … + 98 =
  21. 21.1 + 2 + 3 + … + 76 =
  22. 22.1 + 2 + 3 + … + 40 =
  23. 23.1 + 2 + 3 + … + 79 =
  24. 24.1 + 3 + 5 + … + 45 =
  25. 25.1 + 2 + 3 + … + 21 =
  26. 26.1 + 3 + 5 + … + 41 =
  27. 27.1 + 2 + 3 + … + 6 =
  28. 28.1 + 2 + 3 + … + 33 =
  29. 29.1 + 2 + 3 + … + 15 =
  30. 30.1 + 2 + 3 + … + 63 =
  31. 31.1 + 2 + 3 + … + 97 =
  32. 32.1 + 2 + 3 + … + 20 =
  33. 33.1 + 2 + 3 + … + 96 =
  34. 34.1 + 2 + 3 + … + 88 =
  35. 35.1 + 3 + 5 + … + 35 =
  36. 36.1 + 3 + 5 + … + 43 =
  37. 37.1 + 2 + 3 + … + 37 =
  38. 38.1 + 2 + 3 + … + 8 =
  39. 39.1 + 2 + 3 + … + 62 =
  40. 40.1 + 2 + 3 + … + 18 =

Answer key

  1. 78
  2. 625
  3. 81
  4. 25
  5. 1275
  6. 361
  7. 3655
  8. 253
  9. 496
  10. 144
  11. 325
  12. 5050
  13. 196
  14. 2850
  15. 2080
  16. 66
  17. 225
  18. 2701
  19. 351
  20. 4851
  21. 2926
  22. 820
  23. 3160
  24. 529
  25. 231
  26. 441
  27. 21
  28. 561
  29. 120
  30. 2016
  31. 4753
  32. 210
  33. 4656
  34. 3916
  35. 324
  36. 484
  37. 703
  38. 36
  39. 1953
  40. 171

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