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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 965 · 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 + … + 14 =
  2. 2.1 + 2 + 3 + … + 77 =
  3. 3.1 + 2 + 3 + … + 62 =
  4. 4.1 + 3 + 5 + … + 13 =
  5. 5.1 + 3 + 5 + … + 11 =
  6. 6.1 + 2 + 3 + … + 30 =
  7. 7.1 + 2 + 3 + … + 11 =
  8. 8.1 + 2 + 3 + … + 32 =
  9. 9.1 + 2 + 3 + … + 66 =
  10. 10.1 + 2 + 3 + … + 61 =
  11. 11.1 + 3 + 5 + … + 17 =
  12. 12.1 + 2 + 3 + … + 71 =
  13. 13.1 + 2 + 3 + … + 23 =
  14. 14.1 + 2 + 3 + … + 18 =
  15. 15.1 + 2 + 3 + … + 31 =
  16. 16.1 + 3 + 5 + … + 31 =
  17. 17.1 + 2 + 3 + … + 24 =
  18. 18.1 + 3 + 5 + … + 23 =
  19. 19.1 + 2 + 3 + … + 7 =
  20. 20.1 + 2 + 3 + … + 37 =
  21. 21.1 + 3 + 5 + … + 39 =
  22. 22.1 + 2 + 3 + … + 34 =
  23. 23.1 + 2 + 3 + … + 67 =
  24. 24.1 + 2 + 3 + … + 21 =
  25. 25.1 + 2 + 3 + … + 48 =
  26. 26.1 + 3 + 5 + … + 45 =
  27. 27.1 + 2 + 3 + … + 46 =
  28. 28.1 + 2 + 3 + … + 69 =
  29. 29.1 + 2 + 3 + … + 38 =
  30. 30.1 + 2 + 3 + … + 12 =
  31. 31.1 + 3 + 5 + … + 15 =
  32. 32.1 + 2 + 3 + … + 10 =
  33. 33.1 + 2 + 3 + … + 29 =
  34. 34.1 + 2 + 3 + … + 28 =
  35. 35.1 + 3 + 5 + … + 27 =
  36. 36.1 + 2 + 3 + … + 81 =
  37. 37.1 + 2 + 3 + … + 63 =
  38. 38.1 + 2 + 3 + … + 44 =
  39. 39.1 + 2 + 3 + … + 92 =
  40. 40.1 + 3 + 5 + … + 43 =

Answer key

  1. 105
  2. 3003
  3. 1953
  4. 49
  5. 36
  6. 465
  7. 66
  8. 528
  9. 2211
  10. 1891
  11. 81
  12. 2556
  13. 276
  14. 171
  15. 496
  16. 256
  17. 300
  18. 144
  19. 28
  20. 703
  21. 400
  22. 595
  23. 2278
  24. 231
  25. 1176
  26. 529
  27. 1081
  28. 2415
  29. 741
  30. 78
  31. 64
  32. 55
  33. 435
  34. 406
  35. 196
  36. 3321
  37. 2016
  38. 990
  39. 4278
  40. 484

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