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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 564 · 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 + … + 9 =
  2. 2.1 + 3 + 5 + … + 43 =
  3. 3.1 + 2 + 3 + … + 33 =
  4. 4.1 + 2 + 3 + … + 36 =
  5. 5.1 + 3 + 5 + … + 29 =
  6. 6.1 + 3 + 5 + … + 37 =
  7. 7.1 + 2 + 3 + … + 69 =
  8. 8.1 + 2 + 3 + … + 27 =
  9. 9.1 + 3 + 5 + … + 13 =
  10. 10.1 + 2 + 3 + … + 85 =
  11. 11.1 + 3 + 5 + … + 41 =
  12. 12.1 + 2 + 3 + … + 75 =
  13. 13.1 + 3 + 5 + … + 17 =
  14. 14.1 + 2 + 3 + … + 84 =
  15. 15.1 + 2 + 3 + … + 39 =
  16. 16.1 + 2 + 3 + … + 51 =
  17. 17.1 + 2 + 3 + … + 70 =
  18. 18.1 + 2 + 3 + … + 25 =
  19. 19.1 + 2 + 3 + … + 56 =
  20. 20.1 + 2 + 3 + … + 86 =
  21. 21.1 + 2 + 3 + … + 13 =
  22. 22.1 + 3 + 5 + … + 47 =
  23. 23.1 + 3 + 5 + … + 31 =
  24. 24.1 + 2 + 3 + … + 62 =
  25. 25.1 + 2 + 3 + … + 11 =
  26. 26.1 + 2 + 3 + … + 63 =
  27. 27.1 + 2 + 3 + … + 16 =
  28. 28.1 + 2 + 3 + … + 31 =
  29. 29.1 + 2 + 3 + … + 17 =
  30. 30.1 + 3 + 5 + … + 15 =
  31. 31.1 + 2 + 3 + … + 90 =
  32. 32.1 + 2 + 3 + … + 55 =
  33. 33.1 + 3 + 5 + … + 49 =
  34. 34.1 + 2 + 3 + … + 66 =
  35. 35.1 + 3 + 5 + … + 27 =
  36. 36.1 + 2 + 3 + … + 97 =
  37. 37.1 + 3 + 5 + … + 19 =
  38. 38.1 + 2 + 3 + … + 78 =
  39. 39.1 + 3 + 5 + … + 35 =
  40. 40.1 + 2 + 3 + … + 93 =

Answer key

  1. 25
  2. 484
  3. 561
  4. 666
  5. 225
  6. 361
  7. 2415
  8. 378
  9. 49
  10. 3655
  11. 441
  12. 2850
  13. 81
  14. 3570
  15. 780
  16. 1326
  17. 2485
  18. 325
  19. 1596
  20. 3741
  21. 91
  22. 576
  23. 256
  24. 1953
  25. 66
  26. 2016
  27. 136
  28. 496
  29. 153
  30. 64
  31. 4095
  32. 1540
  33. 625
  34. 2211
  35. 196
  36. 4753
  37. 100
  38. 3081
  39. 324
  40. 4371

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