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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 812 · 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 + … + 33 =
  2. 2.1 + 2 + 3 + … + 30 =
  3. 3.1 + 2 + 3 + … + 56 =
  4. 4.1 + 3 + 5 + … + 19 =
  5. 5.1 + 3 + 5 + … + 17 =
  6. 6.1 + 2 + 3 + … + 19 =
  7. 7.1 + 2 + 3 + … + 23 =
  8. 8.1 + 2 + 3 + … + 25 =
  9. 9.1 + 3 + 5 + … + 29 =
  10. 10.1 + 2 + 3 + … + 16 =
  11. 11.1 + 3 + 5 + … + 15 =
  12. 12.1 + 2 + 3 + … + 65 =
  13. 13.1 + 2 + 3 + … + 48 =
  14. 14.1 + 2 + 3 + … + 73 =
  15. 15.1 + 3 + 5 + … + 33 =
  16. 16.1 + 2 + 3 + … + 84 =
  17. 17.1 + 3 + 5 + … + 27 =
  18. 18.1 + 3 + 5 + … + 9 =
  19. 19.1 + 3 + 5 + … + 31 =
  20. 20.1 + 2 + 3 + … + 87 =
  21. 21.1 + 2 + 3 + … + 40 =
  22. 22.1 + 2 + 3 + … + 10 =
  23. 23.1 + 2 + 3 + … + 95 =
  24. 24.1 + 2 + 3 + … + 79 =
  25. 25.1 + 3 + 5 + … + 45 =
  26. 26.1 + 3 + 5 + … + 35 =
  27. 27.1 + 2 + 3 + … + 69 =
  28. 28.1 + 2 + 3 + … + 9 =
  29. 29.1 + 2 + 3 + … + 97 =
  30. 30.1 + 3 + 5 + … + 49 =
  31. 31.1 + 2 + 3 + … + 59 =
  32. 32.1 + 2 + 3 + … + 93 =
  33. 33.1 + 2 + 3 + … + 51 =
  34. 34.1 + 2 + 3 + … + 26 =
  35. 35.1 + 2 + 3 + … + 99 =
  36. 36.1 + 2 + 3 + … + 77 =
  37. 37.1 + 3 + 5 + … + 11 =
  38. 38.1 + 2 + 3 + … + 62 =
  39. 39.1 + 3 + 5 + … + 23 =
  40. 40.1 + 2 + 3 + … + 14 =

Answer key

  1. 561
  2. 465
  3. 1596
  4. 100
  5. 81
  6. 190
  7. 276
  8. 325
  9. 225
  10. 136
  11. 64
  12. 2145
  13. 1176
  14. 2701
  15. 289
  16. 3570
  17. 196
  18. 25
  19. 256
  20. 3828
  21. 820
  22. 55
  23. 4560
  24. 3160
  25. 529
  26. 324
  27. 2415
  28. 45
  29. 4753
  30. 625
  31. 1770
  32. 4371
  33. 1326
  34. 351
  35. 4950
  36. 3003
  37. 36
  38. 1953
  39. 144
  40. 105

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