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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 250 · 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 + … + 47 =
  2. 2.1 + 2 + 3 + … + 25 =
  3. 3.1 + 2 + 3 + … + 40 =
  4. 4.1 + 2 + 3 + … + 62 =
  5. 5.1 + 2 + 3 + … + 61 =
  6. 6.1 + 2 + 3 + … + 100 =
  7. 7.1 + 3 + 5 + … + 19 =
  8. 8.1 + 2 + 3 + … + 28 =
  9. 9.1 + 3 + 5 + … + 49 =
  10. 10.1 + 2 + 3 + … + 7 =
  11. 11.1 + 3 + 5 + … + 45 =
  12. 12.1 + 2 + 3 + … + 13 =
  13. 13.1 + 2 + 3 + … + 35 =
  14. 14.1 + 3 + 5 + … + 41 =
  15. 15.1 + 2 + 3 + … + 97 =
  16. 16.1 + 2 + 3 + … + 31 =
  17. 17.1 + 2 + 3 + … + 75 =
  18. 18.1 + 2 + 3 + … + 38 =
  19. 19.1 + 3 + 5 + … + 13 =
  20. 20.1 + 3 + 5 + … + 23 =
  21. 21.1 + 2 + 3 + … + 78 =
  22. 22.1 + 3 + 5 + … + 37 =
  23. 23.1 + 2 + 3 + … + 58 =
  24. 24.1 + 2 + 3 + … + 16 =
  25. 25.1 + 2 + 3 + … + 26 =
  26. 26.1 + 3 + 5 + … + 35 =
  27. 27.1 + 2 + 3 + … + 32 =
  28. 28.1 + 2 + 3 + … + 29 =
  29. 29.1 + 2 + 3 + … + 96 =
  30. 30.1 + 3 + 5 + … + 33 =
  31. 31.1 + 2 + 3 + … + 77 =
  32. 32.1 + 2 + 3 + … + 50 =
  33. 33.1 + 3 + 5 + … + 17 =
  34. 34.1 + 2 + 3 + … + 86 =
  35. 35.1 + 2 + 3 + … + 68 =
  36. 36.1 + 2 + 3 + … + 36 =
  37. 37.1 + 3 + 5 + … + 9 =
  38. 38.1 + 3 + 5 + … + 25 =
  39. 39.1 + 2 + 3 + … + 53 =
  40. 40.1 + 2 + 3 + … + 84 =

Answer key

  1. 576
  2. 325
  3. 820
  4. 1953
  5. 1891
  6. 5050
  7. 100
  8. 406
  9. 625
  10. 28
  11. 529
  12. 91
  13. 630
  14. 441
  15. 4753
  16. 496
  17. 2850
  18. 741
  19. 49
  20. 144
  21. 3081
  22. 361
  23. 1711
  24. 136
  25. 351
  26. 324
  27. 528
  28. 435
  29. 4656
  30. 289
  31. 3003
  32. 1275
  33. 81
  34. 3741
  35. 2346
  36. 666
  37. 25
  38. 169
  39. 1431
  40. 3570

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