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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 423 · 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 + … + 45 =
  2. 2.1 + 2 + 3 + … + 77 =
  3. 3.1 + 2 + 3 + … + 21 =
  4. 4.1 + 2 + 3 + … + 69 =
  5. 5.1 + 2 + 3 + … + 15 =
  6. 6.1 + 2 + 3 + … + 23 =
  7. 7.1 + 3 + 5 + … + 9 =
  8. 8.1 + 2 + 3 + … + 27 =
  9. 9.1 + 2 + 3 + … + 70 =
  10. 10.1 + 2 + 3 + … + 6 =
  11. 11.1 + 2 + 3 + … + 9 =
  12. 12.1 + 2 + 3 + … + 40 =
  13. 13.1 + 2 + 3 + … + 71 =
  14. 14.1 + 2 + 3 + … + 28 =
  15. 15.1 + 2 + 3 + … + 97 =
  16. 16.1 + 2 + 3 + … + 36 =
  17. 17.1 + 2 + 3 + … + 10 =
  18. 18.1 + 2 + 3 + … + 44 =
  19. 19.1 + 2 + 3 + … + 7 =
  20. 20.1 + 2 + 3 + … + 33 =
  21. 21.1 + 3 + 5 + … + 11 =
  22. 22.1 + 2 + 3 + … + 52 =
  23. 23.1 + 3 + 5 + … + 31 =
  24. 24.1 + 2 + 3 + … + 63 =
  25. 25.1 + 2 + 3 + … + 86 =
  26. 26.1 + 2 + 3 + … + 13 =
  27. 27.1 + 2 + 3 + … + 24 =
  28. 28.1 + 2 + 3 + … + 84 =
  29. 29.1 + 3 + 5 + … + 27 =
  30. 30.1 + 2 + 3 + … + 30 =
  31. 31.1 + 3 + 5 + … + 33 =
  32. 32.1 + 2 + 3 + … + 100 =
  33. 33.1 + 2 + 3 + … + 62 =
  34. 34.1 + 3 + 5 + … + 37 =
  35. 35.1 + 2 + 3 + … + 19 =
  36. 36.1 + 3 + 5 + … + 19 =
  37. 37.1 + 2 + 3 + … + 73 =
  38. 38.1 + 2 + 3 + … + 56 =
  39. 39.1 + 3 + 5 + … + 41 =
  40. 40.1 + 2 + 3 + … + 88 =

Answer key

  1. 529
  2. 3003
  3. 231
  4. 2415
  5. 120
  6. 276
  7. 25
  8. 378
  9. 2485
  10. 21
  11. 45
  12. 820
  13. 2556
  14. 406
  15. 4753
  16. 666
  17. 55
  18. 990
  19. 28
  20. 561
  21. 36
  22. 1378
  23. 256
  24. 2016
  25. 3741
  26. 91
  27. 300
  28. 3570
  29. 196
  30. 465
  31. 289
  32. 5050
  33. 1953
  34. 361
  35. 190
  36. 100
  37. 2701
  38. 1596
  39. 441
  40. 3916

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