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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 533 · 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 + … + 49 =
  2. 2.1 + 2 + 3 + … + 39 =
  3. 3.1 + 2 + 3 + … + 85 =
  4. 4.1 + 3 + 5 + … + 43 =
  5. 5.1 + 2 + 3 + … + 86 =
  6. 6.1 + 2 + 3 + … + 65 =
  7. 7.1 + 2 + 3 + … + 25 =
  8. 8.1 + 2 + 3 + … + 81 =
  9. 9.1 + 2 + 3 + … + 48 =
  10. 10.1 + 2 + 3 + … + 44 =
  11. 11.1 + 2 + 3 + … + 59 =
  12. 12.1 + 2 + 3 + … + 68 =
  13. 13.1 + 2 + 3 + … + 100 =
  14. 14.1 + 3 + 5 + … + 35 =
  15. 15.1 + 2 + 3 + … + 92 =
  16. 16.1 + 3 + 5 + … + 9 =
  17. 17.1 + 2 + 3 + … + 58 =
  18. 18.1 + 2 + 3 + … + 42 =
  19. 19.1 + 3 + 5 + … + 29 =
  20. 20.1 + 2 + 3 + … + 74 =
  21. 21.1 + 2 + 3 + … + 10 =
  22. 22.1 + 2 + 3 + … + 76 =
  23. 23.1 + 2 + 3 + … + 33 =
  24. 24.1 + 2 + 3 + … + 11 =
  25. 25.1 + 2 + 3 + … + 56 =
  26. 26.1 + 2 + 3 + … + 12 =
  27. 27.1 + 3 + 5 + … + 15 =
  28. 28.1 + 2 + 3 + … + 99 =
  29. 29.1 + 2 + 3 + … + 51 =
  30. 30.1 + 2 + 3 + … + 28 =
  31. 31.1 + 3 + 5 + … + 37 =
  32. 32.1 + 3 + 5 + … + 11 =
  33. 33.1 + 2 + 3 + … + 27 =
  34. 34.1 + 2 + 3 + … + 14 =
  35. 35.1 + 2 + 3 + … + 97 =
  36. 36.1 + 3 + 5 + … + 19 =
  37. 37.1 + 3 + 5 + … + 45 =
  38. 38.1 + 2 + 3 + … + 37 =
  39. 39.1 + 2 + 3 + … + 32 =
  40. 40.1 + 2 + 3 + … + 73 =

Answer key

  1. 625
  2. 780
  3. 3655
  4. 484
  5. 3741
  6. 2145
  7. 325
  8. 3321
  9. 1176
  10. 990
  11. 1770
  12. 2346
  13. 5050
  14. 324
  15. 4278
  16. 25
  17. 1711
  18. 903
  19. 225
  20. 2775
  21. 55
  22. 2926
  23. 561
  24. 66
  25. 1596
  26. 78
  27. 64
  28. 4950
  29. 1326
  30. 406
  31. 361
  32. 36
  33. 378
  34. 105
  35. 4753
  36. 100
  37. 529
  38. 703
  39. 528
  40. 2701

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