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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 993 · 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 + … + 19 =
  2. 2.1 + 3 + 5 + … + 31 =
  3. 3.1 + 2 + 3 + … + 98 =
  4. 4.1 + 3 + 5 + … + 43 =
  5. 5.1 + 2 + 3 + … + 84 =
  6. 6.1 + 3 + 5 + … + 45 =
  7. 7.1 + 2 + 3 + … + 85 =
  8. 8.1 + 2 + 3 + … + 61 =
  9. 9.1 + 3 + 5 + … + 15 =
  10. 10.1 + 2 + 3 + … + 82 =
  11. 11.1 + 3 + 5 + … + 9 =
  12. 12.1 + 3 + 5 + … + 33 =
  13. 13.1 + 3 + 5 + … + 35 =
  14. 14.1 + 3 + 5 + … + 11 =
  15. 15.1 + 2 + 3 + … + 86 =
  16. 16.1 + 2 + 3 + … + 7 =
  17. 17.1 + 3 + 5 + … + 29 =
  18. 18.1 + 3 + 5 + … + 17 =
  19. 19.1 + 2 + 3 + … + 12 =
  20. 20.1 + 2 + 3 + … + 29 =
  21. 21.1 + 2 + 3 + … + 23 =
  22. 22.1 + 2 + 3 + … + 17 =
  23. 23.1 + 3 + 5 + … + 23 =
  24. 24.1 + 2 + 3 + … + 43 =
  25. 25.1 + 2 + 3 + … + 38 =
  26. 26.1 + 2 + 3 + … + 14 =
  27. 27.1 + 2 + 3 + … + 37 =
  28. 28.1 + 2 + 3 + … + 33 =
  29. 29.1 + 2 + 3 + … + 62 =
  30. 30.1 + 2 + 3 + … + 92 =
  31. 31.1 + 2 + 3 + … + 72 =
  32. 32.1 + 2 + 3 + … + 66 =
  33. 33.1 + 2 + 3 + … + 67 =
  34. 34.1 + 3 + 5 + … + 47 =
  35. 35.1 + 2 + 3 + … + 74 =
  36. 36.1 + 3 + 5 + … + 39 =
  37. 37.1 + 2 + 3 + … + 59 =
  38. 38.1 + 2 + 3 + … + 44 =
  39. 39.1 + 2 + 3 + … + 16 =
  40. 40.1 + 3 + 5 + … + 25 =

Answer key

  1. 100
  2. 256
  3. 4851
  4. 484
  5. 3570
  6. 529
  7. 3655
  8. 1891
  9. 64
  10. 3403
  11. 25
  12. 289
  13. 324
  14. 36
  15. 3741
  16. 28
  17. 225
  18. 81
  19. 78
  20. 435
  21. 276
  22. 153
  23. 144
  24. 946
  25. 741
  26. 105
  27. 703
  28. 561
  29. 1953
  30. 4278
  31. 2628
  32. 2211
  33. 2278
  34. 576
  35. 2775
  36. 400
  37. 1770
  38. 990
  39. 136
  40. 169

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