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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 917 · 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 + … + 61 =
  2. 2.1 + 3 + 5 + … + 33 =
  3. 3.1 + 2 + 3 + … + 84 =
  4. 4.1 + 2 + 3 + … + 13 =
  5. 5.1 + 2 + 3 + … + 70 =
  6. 6.1 + 2 + 3 + … + 85 =
  7. 7.1 + 2 + 3 + … + 59 =
  8. 8.1 + 2 + 3 + … + 74 =
  9. 9.1 + 3 + 5 + … + 9 =
  10. 10.1 + 2 + 3 + … + 40 =
  11. 11.1 + 2 + 3 + … + 19 =
  12. 12.1 + 2 + 3 + … + 22 =
  13. 13.1 + 2 + 3 + … + 44 =
  14. 14.1 + 2 + 3 + … + 64 =
  15. 15.1 + 2 + 3 + … + 68 =
  16. 16.1 + 2 + 3 + … + 8 =
  17. 17.1 + 3 + 5 + … + 35 =
  18. 18.1 + 2 + 3 + … + 30 =
  19. 19.1 + 3 + 5 + … + 47 =
  20. 20.1 + 3 + 5 + … + 13 =
  21. 21.1 + 2 + 3 + … + 62 =
  22. 22.1 + 3 + 5 + … + 49 =
  23. 23.1 + 2 + 3 + … + 96 =
  24. 24.1 + 2 + 3 + … + 42 =
  25. 25.1 + 2 + 3 + … + 71 =
  26. 26.1 + 2 + 3 + … + 24 =
  27. 27.1 + 2 + 3 + … + 14 =
  28. 28.1 + 3 + 5 + … + 29 =
  29. 29.1 + 2 + 3 + … + 21 =
  30. 30.1 + 3 + 5 + … + 23 =
  31. 31.1 + 2 + 3 + … + 28 =
  32. 32.1 + 3 + 5 + … + 27 =
  33. 33.1 + 2 + 3 + … + 49 =
  34. 34.1 + 2 + 3 + … + 50 =
  35. 35.1 + 2 + 3 + … + 51 =
  36. 36.1 + 2 + 3 + … + 73 =
  37. 37.1 + 2 + 3 + … + 6 =
  38. 38.1 + 2 + 3 + … + 82 =
  39. 39.1 + 3 + 5 + … + 43 =
  40. 40.1 + 3 + 5 + … + 11 =

Answer key

  1. 1891
  2. 289
  3. 3570
  4. 91
  5. 2485
  6. 3655
  7. 1770
  8. 2775
  9. 25
  10. 820
  11. 190
  12. 253
  13. 990
  14. 2080
  15. 2346
  16. 36
  17. 324
  18. 465
  19. 576
  20. 49
  21. 1953
  22. 625
  23. 4656
  24. 903
  25. 2556
  26. 300
  27. 105
  28. 225
  29. 231
  30. 144
  31. 406
  32. 196
  33. 1225
  34. 1275
  35. 1326
  36. 2701
  37. 21
  38. 3403
  39. 484
  40. 36

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