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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 684 · 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 + … + 17 =
  2. 2.1 + 2 + 3 + … + 59 =
  3. 3.1 + 3 + 5 + … + 13 =
  4. 4.1 + 2 + 3 + … + 87 =
  5. 5.1 + 3 + 5 + … + 31 =
  6. 6.1 + 2 + 3 + … + 27 =
  7. 7.1 + 2 + 3 + … + 9 =
  8. 8.1 + 2 + 3 + … + 26 =
  9. 9.1 + 3 + 5 + … + 19 =
  10. 10.1 + 2 + 3 + … + 30 =
  11. 11.1 + 2 + 3 + … + 8 =
  12. 12.1 + 2 + 3 + … + 35 =
  13. 13.1 + 3 + 5 + … + 29 =
  14. 14.1 + 2 + 3 + … + 24 =
  15. 15.1 + 2 + 3 + … + 44 =
  16. 16.1 + 2 + 3 + … + 68 =
  17. 17.1 + 3 + 5 + … + 23 =
  18. 18.1 + 3 + 5 + … + 11 =
  19. 19.1 + 2 + 3 + … + 49 =
  20. 20.1 + 3 + 5 + … + 33 =
  21. 21.1 + 2 + 3 + … + 86 =
  22. 22.1 + 2 + 3 + … + 91 =
  23. 23.1 + 2 + 3 + … + 11 =
  24. 24.1 + 3 + 5 + … + 39 =
  25. 25.1 + 2 + 3 + … + 73 =
  26. 26.1 + 2 + 3 + … + 77 =
  27. 27.1 + 2 + 3 + … + 19 =
  28. 28.1 + 3 + 5 + … + 21 =
  29. 29.1 + 2 + 3 + … + 6 =
  30. 30.1 + 2 + 3 + … + 34 =
  31. 31.1 + 2 + 3 + … + 32 =
  32. 32.1 + 2 + 3 + … + 72 =
  33. 33.1 + 3 + 5 + … + 27 =
  34. 34.1 + 2 + 3 + … + 56 =
  35. 35.1 + 2 + 3 + … + 69 =
  36. 36.1 + 2 + 3 + … + 28 =
  37. 37.1 + 2 + 3 + … + 71 =
  38. 38.1 + 2 + 3 + … + 96 =
  39. 39.1 + 2 + 3 + … + 63 =
  40. 40.1 + 2 + 3 + … + 20 =

Answer key

  1. 81
  2. 1770
  3. 49
  4. 3828
  5. 256
  6. 378
  7. 45
  8. 351
  9. 100
  10. 465
  11. 36
  12. 630
  13. 225
  14. 300
  15. 990
  16. 2346
  17. 144
  18. 36
  19. 1225
  20. 289
  21. 3741
  22. 4186
  23. 66
  24. 400
  25. 2701
  26. 3003
  27. 190
  28. 121
  29. 21
  30. 595
  31. 528
  32. 2628
  33. 196
  34. 1596
  35. 2415
  36. 406
  37. 2556
  38. 4656
  39. 2016
  40. 210

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