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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 207 · 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 + … + 75 =
  2. 2.1 + 3 + 5 + … + 25 =
  3. 3.1 + 3 + 5 + … + 23 =
  4. 4.1 + 3 + 5 + … + 17 =
  5. 5.1 + 2 + 3 + … + 22 =
  6. 6.1 + 2 + 3 + … + 69 =
  7. 7.1 + 2 + 3 + … + 7 =
  8. 8.1 + 2 + 3 + … + 55 =
  9. 9.1 + 2 + 3 + … + 86 =
  10. 10.1 + 2 + 3 + … + 32 =
  11. 11.1 + 3 + 5 + … + 37 =
  12. 12.1 + 2 + 3 + … + 58 =
  13. 13.1 + 2 + 3 + … + 13 =
  14. 14.1 + 3 + 5 + … + 47 =
  15. 15.1 + 2 + 3 + … + 95 =
  16. 16.1 + 2 + 3 + … + 19 =
  17. 17.1 + 2 + 3 + … + 89 =
  18. 18.1 + 3 + 5 + … + 31 =
  19. 19.1 + 2 + 3 + … + 68 =
  20. 20.1 + 2 + 3 + … + 61 =
  21. 21.1 + 3 + 5 + … + 29 =
  22. 22.1 + 2 + 3 + … + 23 =
  23. 23.1 + 2 + 3 + … + 53 =
  24. 24.1 + 2 + 3 + … + 41 =
  25. 25.1 + 2 + 3 + … + 44 =
  26. 26.1 + 3 + 5 + … + 43 =
  27. 27.1 + 2 + 3 + … + 100 =
  28. 28.1 + 2 + 3 + … + 97 =
  29. 29.1 + 2 + 3 + … + 85 =
  30. 30.1 + 2 + 3 + … + 78 =
  31. 31.1 + 3 + 5 + … + 9 =
  32. 32.1 + 2 + 3 + … + 25 =
  33. 33.1 + 2 + 3 + … + 92 =
  34. 34.1 + 2 + 3 + … + 72 =
  35. 35.1 + 2 + 3 + … + 73 =
  36. 36.1 + 2 + 3 + … + 51 =
  37. 37.1 + 2 + 3 + … + 87 =
  38. 38.1 + 3 + 5 + … + 33 =
  39. 39.1 + 2 + 3 + … + 64 =
  40. 40.1 + 2 + 3 + … + 8 =

Answer key

  1. 2850
  2. 169
  3. 144
  4. 81
  5. 253
  6. 2415
  7. 28
  8. 1540
  9. 3741
  10. 528
  11. 361
  12. 1711
  13. 91
  14. 576
  15. 4560
  16. 190
  17. 4005
  18. 256
  19. 2346
  20. 1891
  21. 225
  22. 276
  23. 1431
  24. 861
  25. 990
  26. 484
  27. 5050
  28. 4753
  29. 3655
  30. 3081
  31. 25
  32. 325
  33. 4278
  34. 2628
  35. 2701
  36. 1326
  37. 3828
  38. 289
  39. 2080
  40. 36

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