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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 985 · 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 + … + 85 =
  2. 2.1 + 2 + 3 + … + 36 =
  3. 3.1 + 2 + 3 + … + 42 =
  4. 4.1 + 2 + 3 + … + 30 =
  5. 5.1 + 2 + 3 + … + 53 =
  6. 6.1 + 3 + 5 + … + 25 =
  7. 7.1 + 2 + 3 + … + 86 =
  8. 8.1 + 2 + 3 + … + 92 =
  9. 9.1 + 3 + 5 + … + 45 =
  10. 10.1 + 3 + 5 + … + 41 =
  11. 11.1 + 2 + 3 + … + 100 =
  12. 12.1 + 2 + 3 + … + 25 =
  13. 13.1 + 2 + 3 + … + 35 =
  14. 14.1 + 2 + 3 + … + 54 =
  15. 15.1 + 2 + 3 + … + 49 =
  16. 16.1 + 3 + 5 + … + 19 =
  17. 17.1 + 2 + 3 + … + 27 =
  18. 18.1 + 3 + 5 + … + 47 =
  19. 19.1 + 3 + 5 + … + 49 =
  20. 20.1 + 2 + 3 + … + 63 =
  21. 21.1 + 3 + 5 + … + 17 =
  22. 22.1 + 2 + 3 + … + 78 =
  23. 23.1 + 3 + 5 + … + 23 =
  24. 24.1 + 2 + 3 + … + 88 =
  25. 25.1 + 2 + 3 + … + 98 =
  26. 26.1 + 3 + 5 + … + 33 =
  27. 27.1 + 2 + 3 + … + 57 =
  28. 28.1 + 2 + 3 + … + 94 =
  29. 29.1 + 2 + 3 + … + 97 =
  30. 30.1 + 2 + 3 + … + 17 =
  31. 31.1 + 3 + 5 + … + 37 =
  32. 32.1 + 3 + 5 + … + 31 =
  33. 33.1 + 3 + 5 + … + 11 =
  34. 34.1 + 2 + 3 + … + 29 =
  35. 35.1 + 2 + 3 + … + 59 =
  36. 36.1 + 3 + 5 + … + 15 =
  37. 37.1 + 2 + 3 + … + 74 =
  38. 38.1 + 3 + 5 + … + 29 =
  39. 39.1 + 3 + 5 + … + 9 =
  40. 40.1 + 2 + 3 + … + 75 =

Answer key

  1. 3655
  2. 666
  3. 903
  4. 465
  5. 1431
  6. 169
  7. 3741
  8. 4278
  9. 529
  10. 441
  11. 5050
  12. 325
  13. 630
  14. 1485
  15. 1225
  16. 100
  17. 378
  18. 576
  19. 625
  20. 2016
  21. 81
  22. 3081
  23. 144
  24. 3916
  25. 4851
  26. 289
  27. 1653
  28. 4465
  29. 4753
  30. 153
  31. 361
  32. 256
  33. 36
  34. 435
  35. 1770
  36. 64
  37. 2775
  38. 225
  39. 25
  40. 2850

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