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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 816 · 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 + … + 17 =
  2. 2.1 + 2 + 3 + … + 22 =
  3. 3.1 + 2 + 3 + … + 10 =
  4. 4.1 + 2 + 3 + … + 33 =
  5. 5.1 + 2 + 3 + … + 61 =
  6. 6.1 + 2 + 3 + … + 18 =
  7. 7.1 + 2 + 3 + … + 100 =
  8. 8.1 + 2 + 3 + … + 76 =
  9. 9.1 + 2 + 3 + … + 42 =
  10. 10.1 + 2 + 3 + … + 44 =
  11. 11.1 + 2 + 3 + … + 35 =
  12. 12.1 + 2 + 3 + … + 71 =
  13. 13.1 + 2 + 3 + … + 29 =
  14. 14.1 + 3 + 5 + … + 39 =
  15. 15.1 + 2 + 3 + … + 82 =
  16. 16.1 + 2 + 3 + … + 85 =
  17. 17.1 + 2 + 3 + … + 84 =
  18. 18.1 + 2 + 3 + … + 75 =
  19. 19.1 + 2 + 3 + … + 58 =
  20. 20.1 + 2 + 3 + … + 74 =
  21. 21.1 + 3 + 5 + … + 21 =
  22. 22.1 + 2 + 3 + … + 54 =
  23. 23.1 + 2 + 3 + … + 9 =
  24. 24.1 + 3 + 5 + … + 41 =
  25. 25.1 + 2 + 3 + … + 49 =
  26. 26.1 + 2 + 3 + … + 8 =
  27. 27.1 + 2 + 3 + … + 24 =
  28. 28.1 + 2 + 3 + … + 99 =
  29. 29.1 + 2 + 3 + … + 62 =
  30. 30.1 + 2 + 3 + … + 21 =
  31. 31.1 + 2 + 3 + … + 90 =
  32. 32.1 + 2 + 3 + … + 55 =
  33. 33.1 + 2 + 3 + … + 45 =
  34. 34.1 + 2 + 3 + … + 72 =
  35. 35.1 + 2 + 3 + … + 73 =
  36. 36.1 + 2 + 3 + … + 26 =
  37. 37.1 + 3 + 5 + … + 47 =
  38. 38.1 + 3 + 5 + … + 37 =
  39. 39.1 + 2 + 3 + … + 11 =
  40. 40.1 + 2 + 3 + … + 96 =

Answer key

  1. 81
  2. 253
  3. 55
  4. 561
  5. 1891
  6. 171
  7. 5050
  8. 2926
  9. 903
  10. 990
  11. 630
  12. 2556
  13. 435
  14. 400
  15. 3403
  16. 3655
  17. 3570
  18. 2850
  19. 1711
  20. 2775
  21. 121
  22. 1485
  23. 45
  24. 441
  25. 1225
  26. 36
  27. 300
  28. 4950
  29. 1953
  30. 231
  31. 4095
  32. 1540
  33. 1035
  34. 2628
  35. 2701
  36. 351
  37. 576
  38. 361
  39. 66
  40. 4656

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