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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 258 · 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 + … + 15 =
  2. 2.1 + 2 + 3 + … + 17 =
  3. 3.1 + 3 + 5 + … + 47 =
  4. 4.1 + 2 + 3 + … + 35 =
  5. 5.1 + 3 + 5 + … + 35 =
  6. 6.1 + 2 + 3 + … + 100 =
  7. 7.1 + 3 + 5 + … + 41 =
  8. 8.1 + 3 + 5 + … + 43 =
  9. 9.1 + 2 + 3 + … + 14 =
  10. 10.1 + 2 + 3 + … + 25 =
  11. 11.1 + 2 + 3 + … + 9 =
  12. 12.1 + 2 + 3 + … + 86 =
  13. 13.1 + 2 + 3 + … + 33 =
  14. 14.1 + 2 + 3 + … + 36 =
  15. 15.1 + 3 + 5 + … + 27 =
  16. 16.1 + 2 + 3 + … + 74 =
  17. 17.1 + 2 + 3 + … + 60 =
  18. 18.1 + 2 + 3 + … + 30 =
  19. 19.1 + 2 + 3 + … + 96 =
  20. 20.1 + 2 + 3 + … + 71 =
  21. 21.1 + 3 + 5 + … + 45 =
  22. 22.1 + 2 + 3 + … + 38 =
  23. 23.1 + 2 + 3 + … + 15 =
  24. 24.1 + 2 + 3 + … + 57 =
  25. 25.1 + 2 + 3 + … + 84 =
  26. 26.1 + 3 + 5 + … + 33 =
  27. 27.1 + 2 + 3 + … + 63 =
  28. 28.1 + 2 + 3 + … + 73 =
  29. 29.1 + 2 + 3 + … + 7 =
  30. 30.1 + 3 + 5 + … + 49 =
  31. 31.1 + 2 + 3 + … + 58 =
  32. 32.1 + 2 + 3 + … + 62 =
  33. 33.1 + 3 + 5 + … + 11 =
  34. 34.1 + 2 + 3 + … + 20 =
  35. 35.1 + 2 + 3 + … + 95 =
  36. 36.1 + 2 + 3 + … + 72 =
  37. 37.1 + 3 + 5 + … + 31 =
  38. 38.1 + 2 + 3 + … + 55 =
  39. 39.1 + 3 + 5 + … + 17 =
  40. 40.1 + 3 + 5 + … + 25 =

Answer key

  1. 64
  2. 153
  3. 576
  4. 630
  5. 324
  6. 5050
  7. 441
  8. 484
  9. 105
  10. 325
  11. 45
  12. 3741
  13. 561
  14. 666
  15. 196
  16. 2775
  17. 1830
  18. 465
  19. 4656
  20. 2556
  21. 529
  22. 741
  23. 120
  24. 1653
  25. 3570
  26. 289
  27. 2016
  28. 2701
  29. 28
  30. 625
  31. 1711
  32. 1953
  33. 36
  34. 210
  35. 4560
  36. 2628
  37. 256
  38. 1540
  39. 81
  40. 169

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