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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 957 · 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 + … + 39 =
  2. 2.1 + 2 + 3 + … + 74 =
  3. 3.1 + 2 + 3 + … + 56 =
  4. 4.1 + 3 + 5 + … + 17 =
  5. 5.1 + 2 + 3 + … + 77 =
  6. 6.1 + 3 + 5 + … + 45 =
  7. 7.1 + 2 + 3 + … + 98 =
  8. 8.1 + 2 + 3 + … + 99 =
  9. 9.1 + 2 + 3 + … + 34 =
  10. 10.1 + 2 + 3 + … + 54 =
  11. 11.1 + 2 + 3 + … + 50 =
  12. 12.1 + 3 + 5 + … + 11 =
  13. 13.1 + 2 + 3 + … + 13 =
  14. 14.1 + 2 + 3 + … + 23 =
  15. 15.1 + 3 + 5 + … + 23 =
  16. 16.1 + 2 + 3 + … + 27 =
  17. 17.1 + 2 + 3 + … + 67 =
  18. 18.1 + 3 + 5 + … + 25 =
  19. 19.1 + 2 + 3 + … + 25 =
  20. 20.1 + 2 + 3 + … + 17 =
  21. 21.1 + 2 + 3 + … + 45 =
  22. 22.1 + 3 + 5 + … + 13 =
  23. 23.1 + 3 + 5 + … + 35 =
  24. 24.1 + 3 + 5 + … + 21 =
  25. 25.1 + 2 + 3 + … + 83 =
  26. 26.1 + 2 + 3 + … + 65 =
  27. 27.1 + 2 + 3 + … + 14 =
  28. 28.1 + 2 + 3 + … + 88 =
  29. 29.1 + 2 + 3 + … + 21 =
  30. 30.1 + 2 + 3 + … + 90 =
  31. 31.1 + 2 + 3 + … + 22 =
  32. 32.1 + 2 + 3 + … + 33 =
  33. 33.1 + 2 + 3 + … + 100 =
  34. 34.1 + 2 + 3 + … + 70 =
  35. 35.1 + 2 + 3 + … + 38 =
  36. 36.1 + 2 + 3 + … + 59 =
  37. 37.1 + 2 + 3 + … + 76 =
  38. 38.1 + 3 + 5 + … + 19 =
  39. 39.1 + 2 + 3 + … + 62 =
  40. 40.1 + 3 + 5 + … + 41 =

Answer key

  1. 400
  2. 2775
  3. 1596
  4. 81
  5. 3003
  6. 529
  7. 4851
  8. 4950
  9. 595
  10. 1485
  11. 1275
  12. 36
  13. 91
  14. 276
  15. 144
  16. 378
  17. 2278
  18. 169
  19. 325
  20. 153
  21. 1035
  22. 49
  23. 324
  24. 121
  25. 3486
  26. 2145
  27. 105
  28. 3916
  29. 231
  30. 4095
  31. 253
  32. 561
  33. 5050
  34. 2485
  35. 741
  36. 1770
  37. 2926
  38. 100
  39. 1953
  40. 441

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