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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 968 · 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 + … + 19 =
  2. 2.1 + 2 + 3 + … + 51 =
  3. 3.1 + 2 + 3 + … + 41 =
  4. 4.1 + 2 + 3 + … + 23 =
  5. 5.1 + 2 + 3 + … + 91 =
  6. 6.1 + 2 + 3 + … + 12 =
  7. 7.1 + 3 + 5 + … + 35 =
  8. 8.1 + 2 + 3 + … + 97 =
  9. 9.1 + 2 + 3 + … + 38 =
  10. 10.1 + 3 + 5 + … + 15 =
  11. 11.1 + 2 + 3 + … + 61 =
  12. 12.1 + 3 + 5 + … + 49 =
  13. 13.1 + 2 + 3 + … + 96 =
  14. 14.1 + 2 + 3 + … + 44 =
  15. 15.1 + 3 + 5 + … + 25 =
  16. 16.1 + 3 + 5 + … + 39 =
  17. 17.1 + 3 + 5 + … + 17 =
  18. 18.1 + 3 + 5 + … + 11 =
  19. 19.1 + 2 + 3 + … + 26 =
  20. 20.1 + 2 + 3 + … + 56 =
  21. 21.1 + 2 + 3 + … + 17 =
  22. 22.1 + 3 + 5 + … + 33 =
  23. 23.1 + 3 + 5 + … + 27 =
  24. 24.1 + 2 + 3 + … + 31 =
  25. 25.1 + 2 + 3 + … + 81 =
  26. 26.1 + 2 + 3 + … + 16 =
  27. 27.1 + 2 + 3 + … + 11 =
  28. 28.1 + 2 + 3 + … + 76 =
  29. 29.1 + 3 + 5 + … + 47 =
  30. 30.1 + 2 + 3 + … + 93 =
  31. 31.1 + 2 + 3 + … + 27 =
  32. 32.1 + 2 + 3 + … + 10 =
  33. 33.1 + 2 + 3 + … + 100 =
  34. 34.1 + 2 + 3 + … + 9 =
  35. 35.1 + 2 + 3 + … + 32 =
  36. 36.1 + 2 + 3 + … + 58 =
  37. 37.1 + 2 + 3 + … + 52 =
  38. 38.1 + 2 + 3 + … + 69 =
  39. 39.1 + 3 + 5 + … + 9 =
  40. 40.1 + 2 + 3 + … + 40 =

Answer key

  1. 100
  2. 1326
  3. 861
  4. 276
  5. 4186
  6. 78
  7. 324
  8. 4753
  9. 741
  10. 64
  11. 1891
  12. 625
  13. 4656
  14. 990
  15. 169
  16. 400
  17. 81
  18. 36
  19. 351
  20. 1596
  21. 153
  22. 289
  23. 196
  24. 496
  25. 3321
  26. 136
  27. 66
  28. 2926
  29. 576
  30. 4371
  31. 378
  32. 55
  33. 5050
  34. 45
  35. 528
  36. 1711
  37. 1378
  38. 2415
  39. 25
  40. 820

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