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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 191 · 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 + … + 31 =
  2. 2.1 + 3 + 5 + … + 25 =
  3. 3.1 + 3 + 5 + … + 11 =
  4. 4.1 + 2 + 3 + … + 100 =
  5. 5.1 + 2 + 3 + … + 64 =
  6. 6.1 + 3 + 5 + … + 9 =
  7. 7.1 + 2 + 3 + … + 81 =
  8. 8.1 + 2 + 3 + … + 7 =
  9. 9.1 + 2 + 3 + … + 40 =
  10. 10.1 + 2 + 3 + … + 52 =
  11. 11.1 + 2 + 3 + … + 35 =
  12. 12.1 + 2 + 3 + … + 44 =
  13. 13.1 + 2 + 3 + … + 53 =
  14. 14.1 + 2 + 3 + … + 92 =
  15. 15.1 + 2 + 3 + … + 17 =
  16. 16.1 + 3 + 5 + … + 17 =
  17. 17.1 + 2 + 3 + … + 29 =
  18. 18.1 + 2 + 3 + … + 89 =
  19. 19.1 + 2 + 3 + … + 32 =
  20. 20.1 + 3 + 5 + … + 41 =
  21. 21.1 + 2 + 3 + … + 60 =
  22. 22.1 + 2 + 3 + … + 75 =
  23. 23.1 + 2 + 3 + … + 57 =
  24. 24.1 + 2 + 3 + … + 19 =
  25. 25.1 + 2 + 3 + … + 61 =
  26. 26.1 + 2 + 3 + … + 88 =
  27. 27.1 + 2 + 3 + … + 79 =
  28. 28.1 + 2 + 3 + … + 96 =
  29. 29.1 + 2 + 3 + … + 10 =
  30. 30.1 + 2 + 3 + … + 28 =
  31. 31.1 + 2 + 3 + … + 74 =
  32. 32.1 + 3 + 5 + … + 19 =
  33. 33.1 + 3 + 5 + … + 23 =
  34. 34.1 + 2 + 3 + … + 87 =
  35. 35.1 + 3 + 5 + … + 45 =
  36. 36.1 + 2 + 3 + … + 71 =
  37. 37.1 + 2 + 3 + … + 16 =
  38. 38.1 + 2 + 3 + … + 26 =
  39. 39.1 + 2 + 3 + … + 97 =
  40. 40.1 + 3 + 5 + … + 49 =

Answer key

  1. 256
  2. 169
  3. 36
  4. 5050
  5. 2080
  6. 25
  7. 3321
  8. 28
  9. 820
  10. 1378
  11. 630
  12. 990
  13. 1431
  14. 4278
  15. 153
  16. 81
  17. 435
  18. 4005
  19. 528
  20. 441
  21. 1830
  22. 2850
  23. 1653
  24. 190
  25. 1891
  26. 3916
  27. 3160
  28. 4656
  29. 55
  30. 406
  31. 2775
  32. 100
  33. 144
  34. 3828
  35. 529
  36. 2556
  37. 136
  38. 351
  39. 4753
  40. 625

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