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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 141 · 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 + … + 97 =
  2. 2.1 + 2 + 3 + … + 6 =
  3. 3.1 + 3 + 5 + … + 13 =
  4. 4.1 + 2 + 3 + … + 85 =
  5. 5.1 + 3 + 5 + … + 17 =
  6. 6.1 + 2 + 3 + … + 7 =
  7. 7.1 + 3 + 5 + … + 11 =
  8. 8.1 + 2 + 3 + … + 42 =
  9. 9.1 + 3 + 5 + … + 15 =
  10. 10.1 + 2 + 3 + … + 14 =
  11. 11.1 + 2 + 3 + … + 71 =
  12. 12.1 + 2 + 3 + … + 70 =
  13. 13.1 + 2 + 3 + … + 89 =
  14. 14.1 + 2 + 3 + … + 99 =
  15. 15.1 + 2 + 3 + … + 100 =
  16. 16.1 + 2 + 3 + … + 47 =
  17. 17.1 + 2 + 3 + … + 39 =
  18. 18.1 + 3 + 5 + … + 49 =
  19. 19.1 + 2 + 3 + … + 15 =
  20. 20.1 + 3 + 5 + … + 19 =
  21. 21.1 + 3 + 5 + … + 25 =
  22. 22.1 + 2 + 3 + … + 51 =
  23. 23.1 + 2 + 3 + … + 23 =
  24. 24.1 + 2 + 3 + … + 92 =
  25. 25.1 + 3 + 5 + … + 45 =
  26. 26.1 + 2 + 3 + … + 94 =
  27. 27.1 + 3 + 5 + … + 41 =
  28. 28.1 + 2 + 3 + … + 30 =
  29. 29.1 + 2 + 3 + … + 8 =
  30. 30.1 + 2 + 3 + … + 54 =
  31. 31.1 + 3 + 5 + … + 43 =
  32. 32.1 + 2 + 3 + … + 33 =
  33. 33.1 + 2 + 3 + … + 88 =
  34. 34.1 + 2 + 3 + … + 61 =
  35. 35.1 + 3 + 5 + … + 27 =
  36. 36.1 + 2 + 3 + … + 16 =
  37. 37.1 + 2 + 3 + … + 90 =
  38. 38.1 + 2 + 3 + … + 86 =
  39. 39.1 + 2 + 3 + … + 75 =
  40. 40.1 + 3 + 5 + … + 21 =

Answer key

  1. 4753
  2. 21
  3. 49
  4. 3655
  5. 81
  6. 28
  7. 36
  8. 903
  9. 64
  10. 105
  11. 2556
  12. 2485
  13. 4005
  14. 4950
  15. 5050
  16. 1128
  17. 780
  18. 625
  19. 120
  20. 100
  21. 169
  22. 1326
  23. 276
  24. 4278
  25. 529
  26. 4465
  27. 441
  28. 465
  29. 36
  30. 1485
  31. 484
  32. 561
  33. 3916
  34. 1891
  35. 196
  36. 136
  37. 4095
  38. 3741
  39. 2850
  40. 121

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