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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 204 · 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 + … + 98 =
  2. 2.1 + 3 + 5 + … + 39 =
  3. 3.1 + 2 + 3 + … + 54 =
  4. 4.1 + 2 + 3 + … + 20 =
  5. 5.1 + 2 + 3 + … + 28 =
  6. 6.1 + 2 + 3 + … + 23 =
  7. 7.1 + 2 + 3 + … + 27 =
  8. 8.1 + 2 + 3 + … + 37 =
  9. 9.1 + 2 + 3 + … + 68 =
  10. 10.1 + 3 + 5 + … + 21 =
  11. 11.1 + 2 + 3 + … + 99 =
  12. 12.1 + 2 + 3 + … + 18 =
  13. 13.1 + 2 + 3 + … + 58 =
  14. 14.1 + 2 + 3 + … + 13 =
  15. 15.1 + 2 + 3 + … + 64 =
  16. 16.1 + 2 + 3 + … + 84 =
  17. 17.1 + 3 + 5 + … + 49 =
  18. 18.1 + 2 + 3 + … + 77 =
  19. 19.1 + 2 + 3 + … + 36 =
  20. 20.1 + 2 + 3 + … + 96 =
  21. 21.1 + 3 + 5 + … + 37 =
  22. 22.1 + 3 + 5 + … + 25 =
  23. 23.1 + 3 + 5 + … + 35 =
  24. 24.1 + 3 + 5 + … + 45 =
  25. 25.1 + 2 + 3 + … + 25 =
  26. 26.1 + 3 + 5 + … + 15 =
  27. 27.1 + 2 + 3 + … + 21 =
  28. 28.1 + 2 + 3 + … + 51 =
  29. 29.1 + 3 + 5 + … + 9 =
  30. 30.1 + 2 + 3 + … + 12 =
  31. 31.1 + 3 + 5 + … + 17 =
  32. 32.1 + 2 + 3 + … + 32 =
  33. 33.1 + 2 + 3 + … + 39 =
  34. 34.1 + 2 + 3 + … + 6 =
  35. 35.1 + 2 + 3 + … + 89 =
  36. 36.1 + 2 + 3 + … + 61 =
  37. 37.1 + 3 + 5 + … + 33 =
  38. 38.1 + 2 + 3 + … + 71 =
  39. 39.1 + 2 + 3 + … + 14 =
  40. 40.1 + 3 + 5 + … + 11 =

Answer key

  1. 4851
  2. 400
  3. 1485
  4. 210
  5. 406
  6. 276
  7. 378
  8. 703
  9. 2346
  10. 121
  11. 4950
  12. 171
  13. 1711
  14. 91
  15. 2080
  16. 3570
  17. 625
  18. 3003
  19. 666
  20. 4656
  21. 361
  22. 169
  23. 324
  24. 529
  25. 325
  26. 64
  27. 231
  28. 1326
  29. 25
  30. 78
  31. 81
  32. 528
  33. 780
  34. 21
  35. 4005
  36. 1891
  37. 289
  38. 2556
  39. 105
  40. 36

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