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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 708 · 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 + … + 11 =
  2. 2.1 + 2 + 3 + … + 77 =
  3. 3.1 + 2 + 3 + … + 70 =
  4. 4.1 + 2 + 3 + … + 42 =
  5. 5.1 + 2 + 3 + … + 29 =
  6. 6.1 + 2 + 3 + … + 81 =
  7. 7.1 + 2 + 3 + … + 9 =
  8. 8.1 + 3 + 5 + … + 19 =
  9. 9.1 + 2 + 3 + … + 48 =
  10. 10.1 + 3 + 5 + … + 25 =
  11. 11.1 + 3 + 5 + … + 47 =
  12. 12.1 + 2 + 3 + … + 90 =
  13. 13.1 + 2 + 3 + … + 27 =
  14. 14.1 + 3 + 5 + … + 31 =
  15. 15.1 + 2 + 3 + … + 63 =
  16. 16.1 + 2 + 3 + … + 56 =
  17. 17.1 + 2 + 3 + … + 75 =
  18. 18.1 + 2 + 3 + … + 98 =
  19. 19.1 + 2 + 3 + … + 16 =
  20. 20.1 + 2 + 3 + … + 14 =
  21. 21.1 + 2 + 3 + … + 19 =
  22. 22.1 + 3 + 5 + … + 35 =
  23. 23.1 + 2 + 3 + … + 66 =
  24. 24.1 + 2 + 3 + … + 6 =
  25. 25.1 + 2 + 3 + … + 73 =
  26. 26.1 + 3 + 5 + … + 37 =
  27. 27.1 + 2 + 3 + … + 79 =
  28. 28.1 + 2 + 3 + … + 22 =
  29. 29.1 + 2 + 3 + … + 32 =
  30. 30.1 + 3 + 5 + … + 43 =
  31. 31.1 + 3 + 5 + … + 45 =
  32. 32.1 + 2 + 3 + … + 24 =
  33. 33.1 + 2 + 3 + … + 100 =
  34. 34.1 + 3 + 5 + … + 17 =
  35. 35.1 + 2 + 3 + … + 13 =
  36. 36.1 + 2 + 3 + … + 62 =
  37. 37.1 + 2 + 3 + … + 39 =
  38. 38.1 + 2 + 3 + … + 89 =
  39. 39.1 + 2 + 3 + … + 43 =
  40. 40.1 + 2 + 3 + … + 26 =

Answer key

  1. 36
  2. 3003
  3. 2485
  4. 903
  5. 435
  6. 3321
  7. 45
  8. 100
  9. 1176
  10. 169
  11. 576
  12. 4095
  13. 378
  14. 256
  15. 2016
  16. 1596
  17. 2850
  18. 4851
  19. 136
  20. 105
  21. 190
  22. 324
  23. 2211
  24. 21
  25. 2701
  26. 361
  27. 3160
  28. 253
  29. 528
  30. 484
  31. 529
  32. 300
  33. 5050
  34. 81
  35. 91
  36. 1953
  37. 780
  38. 4005
  39. 946
  40. 351

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