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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 655 · 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 + … + 91 =
  2. 2.1 + 2 + 3 + … + 11 =
  3. 3.1 + 2 + 3 + … + 68 =
  4. 4.1 + 2 + 3 + … + 14 =
  5. 5.1 + 3 + 5 + … + 17 =
  6. 6.1 + 2 + 3 + … + 63 =
  7. 7.1 + 3 + 5 + … + 37 =
  8. 8.1 + 3 + 5 + … + 13 =
  9. 9.1 + 2 + 3 + … + 88 =
  10. 10.1 + 3 + 5 + … + 27 =
  11. 11.1 + 3 + 5 + … + 45 =
  12. 12.1 + 2 + 3 + … + 29 =
  13. 13.1 + 3 + 5 + … + 25 =
  14. 14.1 + 2 + 3 + … + 15 =
  15. 15.1 + 2 + 3 + … + 19 =
  16. 16.1 + 2 + 3 + … + 99 =
  17. 17.1 + 2 + 3 + … + 84 =
  18. 18.1 + 2 + 3 + … + 44 =
  19. 19.1 + 2 + 3 + … + 81 =
  20. 20.1 + 2 + 3 + … + 43 =
  21. 21.1 + 2 + 3 + … + 66 =
  22. 22.1 + 2 + 3 + … + 28 =
  23. 23.1 + 3 + 5 + … + 43 =
  24. 24.1 + 2 + 3 + … + 76 =
  25. 25.1 + 3 + 5 + … + 21 =
  26. 26.1 + 2 + 3 + … + 96 =
  27. 27.1 + 2 + 3 + … + 55 =
  28. 28.1 + 2 + 3 + … + 69 =
  29. 29.1 + 2 + 3 + … + 92 =
  30. 30.1 + 3 + 5 + … + 31 =
  31. 31.1 + 2 + 3 + … + 39 =
  32. 32.1 + 2 + 3 + … + 70 =
  33. 33.1 + 2 + 3 + … + 61 =
  34. 34.1 + 2 + 3 + … + 53 =
  35. 35.1 + 2 + 3 + … + 25 =
  36. 36.1 + 2 + 3 + … + 59 =
  37. 37.1 + 2 + 3 + … + 90 =
  38. 38.1 + 2 + 3 + … + 64 =
  39. 39.1 + 2 + 3 + … + 93 =
  40. 40.1 + 2 + 3 + … + 60 =

Answer key

  1. 4186
  2. 66
  3. 2346
  4. 105
  5. 81
  6. 2016
  7. 361
  8. 49
  9. 3916
  10. 196
  11. 529
  12. 435
  13. 169
  14. 120
  15. 190
  16. 4950
  17. 3570
  18. 990
  19. 3321
  20. 946
  21. 2211
  22. 406
  23. 484
  24. 2926
  25. 121
  26. 4656
  27. 1540
  28. 2415
  29. 4278
  30. 256
  31. 780
  32. 2485
  33. 1891
  34. 1431
  35. 325
  36. 1770
  37. 4095
  38. 2080
  39. 4371
  40. 1830

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