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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 565 · 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 + 3 + 5 + … + 17 =
  3. 3.1 + 2 + 3 + … + 74 =
  4. 4.1 + 2 + 3 + … + 66 =
  5. 5.1 + 2 + 3 + … + 62 =
  6. 6.1 + 2 + 3 + … + 30 =
  7. 7.1 + 3 + 5 + … + 13 =
  8. 8.1 + 2 + 3 + … + 19 =
  9. 9.1 + 2 + 3 + … + 17 =
  10. 10.1 + 2 + 3 + … + 36 =
  11. 11.1 + 3 + 5 + … + 47 =
  12. 12.1 + 3 + 5 + … + 45 =
  13. 13.1 + 2 + 3 + … + 41 =
  14. 14.1 + 2 + 3 + … + 33 =
  15. 15.1 + 3 + 5 + … + 29 =
  16. 16.1 + 2 + 3 + … + 76 =
  17. 17.1 + 2 + 3 + … + 10 =
  18. 18.1 + 2 + 3 + … + 90 =
  19. 19.1 + 2 + 3 + … + 29 =
  20. 20.1 + 2 + 3 + … + 15 =
  21. 21.1 + 2 + 3 + … + 83 =
  22. 22.1 + 2 + 3 + … + 6 =
  23. 23.1 + 2 + 3 + … + 7 =
  24. 24.1 + 2 + 3 + … + 13 =
  25. 25.1 + 2 + 3 + … + 48 =
  26. 26.1 + 2 + 3 + … + 8 =
  27. 27.1 + 3 + 5 + … + 23 =
  28. 28.1 + 3 + 5 + … + 43 =
  29. 29.1 + 3 + 5 + … + 9 =
  30. 30.1 + 3 + 5 + … + 37 =
  31. 31.1 + 2 + 3 + … + 60 =
  32. 32.1 + 2 + 3 + … + 59 =
  33. 33.1 + 3 + 5 + … + 19 =
  34. 34.1 + 3 + 5 + … + 33 =
  35. 35.1 + 2 + 3 + … + 37 =
  36. 36.1 + 2 + 3 + … + 67 =
  37. 37.1 + 2 + 3 + … + 100 =
  38. 38.1 + 2 + 3 + … + 14 =
  39. 39.1 + 2 + 3 + … + 73 =
  40. 40.1 + 3 + 5 + … + 11 =

Answer key

  1. 64
  2. 81
  3. 2775
  4. 2211
  5. 1953
  6. 465
  7. 49
  8. 190
  9. 153
  10. 666
  11. 576
  12. 529
  13. 861
  14. 561
  15. 225
  16. 2926
  17. 55
  18. 4095
  19. 435
  20. 120
  21. 3486
  22. 21
  23. 28
  24. 91
  25. 1176
  26. 36
  27. 144
  28. 484
  29. 25
  30. 361
  31. 1830
  32. 1770
  33. 100
  34. 289
  35. 703
  36. 2278
  37. 5050
  38. 105
  39. 2701
  40. 36

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