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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 235 · 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 + … + 35 =
  2. 2.1 + 2 + 3 + … + 13 =
  3. 3.1 + 2 + 3 + … + 29 =
  4. 4.1 + 2 + 3 + … + 60 =
  5. 5.1 + 2 + 3 + … + 18 =
  6. 6.1 + 2 + 3 + … + 14 =
  7. 7.1 + 2 + 3 + … + 34 =
  8. 8.1 + 2 + 3 + … + 33 =
  9. 9.1 + 2 + 3 + … + 79 =
  10. 10.1 + 2 + 3 + … + 7 =
  11. 11.1 + 2 + 3 + … + 27 =
  12. 12.1 + 3 + 5 + … + 11 =
  13. 13.1 + 2 + 3 + … + 52 =
  14. 14.1 + 3 + 5 + … + 47 =
  15. 15.1 + 3 + 5 + … + 25 =
  16. 16.1 + 3 + 5 + … + 21 =
  17. 17.1 + 2 + 3 + … + 31 =
  18. 18.1 + 2 + 3 + … + 28 =
  19. 19.1 + 3 + 5 + … + 19 =
  20. 20.1 + 3 + 5 + … + 45 =
  21. 21.1 + 3 + 5 + … + 27 =
  22. 22.1 + 2 + 3 + … + 70 =
  23. 23.1 + 3 + 5 + … + 43 =
  24. 24.1 + 2 + 3 + … + 64 =
  25. 25.1 + 3 + 5 + … + 13 =
  26. 26.1 + 2 + 3 + … + 90 =
  27. 27.1 + 2 + 3 + … + 75 =
  28. 28.1 + 2 + 3 + … + 97 =
  29. 29.1 + 3 + 5 + … + 33 =
  30. 30.1 + 2 + 3 + … + 98 =
  31. 31.1 + 2 + 3 + … + 83 =
  32. 32.1 + 2 + 3 + … + 30 =
  33. 33.1 + 2 + 3 + … + 81 =
  34. 34.1 + 2 + 3 + … + 61 =
  35. 35.1 + 2 + 3 + … + 66 =
  36. 36.1 + 2 + 3 + … + 15 =
  37. 37.1 + 3 + 5 + … + 17 =
  38. 38.1 + 2 + 3 + … + 85 =
  39. 39.1 + 2 + 3 + … + 91 =
  40. 40.1 + 2 + 3 + … + 51 =

Answer key

  1. 324
  2. 91
  3. 435
  4. 1830
  5. 171
  6. 105
  7. 595
  8. 561
  9. 3160
  10. 28
  11. 378
  12. 36
  13. 1378
  14. 576
  15. 169
  16. 121
  17. 496
  18. 406
  19. 100
  20. 529
  21. 196
  22. 2485
  23. 484
  24. 2080
  25. 49
  26. 4095
  27. 2850
  28. 4753
  29. 289
  30. 4851
  31. 3486
  32. 465
  33. 3321
  34. 1891
  35. 2211
  36. 120
  37. 81
  38. 3655
  39. 4186
  40. 1326

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