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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 63 · 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 + … + 75 =
  2. 2.1 + 3 + 5 + … + 47 =
  3. 3.1 + 2 + 3 + … + 97 =
  4. 4.1 + 2 + 3 + … + 62 =
  5. 5.1 + 2 + 3 + … + 53 =
  6. 6.1 + 2 + 3 + … + 8 =
  7. 7.1 + 2 + 3 + … + 35 =
  8. 8.1 + 2 + 3 + … + 39 =
  9. 9.1 + 2 + 3 + … + 6 =
  10. 10.1 + 2 + 3 + … + 23 =
  11. 11.1 + 2 + 3 + … + 77 =
  12. 12.1 + 2 + 3 + … + 37 =
  13. 13.1 + 3 + 5 + … + 45 =
  14. 14.1 + 2 + 3 + … + 96 =
  15. 15.1 + 2 + 3 + … + 59 =
  16. 16.1 + 2 + 3 + … + 73 =
  17. 17.1 + 3 + 5 + … + 19 =
  18. 18.1 + 2 + 3 + … + 32 =
  19. 19.1 + 2 + 3 + … + 66 =
  20. 20.1 + 3 + 5 + … + 33 =
  21. 21.1 + 3 + 5 + … + 43 =
  22. 22.1 + 3 + 5 + … + 21 =
  23. 23.1 + 2 + 3 + … + 60 =
  24. 24.1 + 2 + 3 + … + 44 =
  25. 25.1 + 2 + 3 + … + 74 =
  26. 26.1 + 3 + 5 + … + 15 =
  27. 27.1 + 2 + 3 + … + 58 =
  28. 28.1 + 2 + 3 + … + 83 =
  29. 29.1 + 2 + 3 + … + 14 =
  30. 30.1 + 2 + 3 + … + 56 =
  31. 31.1 + 3 + 5 + … + 11 =
  32. 32.1 + 3 + 5 + … + 29 =
  33. 33.1 + 2 + 3 + … + 20 =
  34. 34.1 + 2 + 3 + … + 63 =
  35. 35.1 + 3 + 5 + … + 17 =
  36. 36.1 + 2 + 3 + … + 9 =
  37. 37.1 + 2 + 3 + … + 40 =
  38. 38.1 + 2 + 3 + … + 78 =
  39. 39.1 + 3 + 5 + … + 9 =
  40. 40.1 + 2 + 3 + … + 18 =

Answer key

  1. 2850
  2. 576
  3. 4753
  4. 1953
  5. 1431
  6. 36
  7. 630
  8. 780
  9. 21
  10. 276
  11. 3003
  12. 703
  13. 529
  14. 4656
  15. 1770
  16. 2701
  17. 100
  18. 528
  19. 2211
  20. 289
  21. 484
  22. 121
  23. 1830
  24. 990
  25. 2775
  26. 64
  27. 1711
  28. 3486
  29. 105
  30. 1596
  31. 36
  32. 225
  33. 210
  34. 2016
  35. 81
  36. 45
  37. 820
  38. 3081
  39. 25
  40. 171

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