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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 242 · 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 + … + 27 =
  2. 2.1 + 2 + 3 + … + 34 =
  3. 3.1 + 2 + 3 + … + 80 =
  4. 4.1 + 3 + 5 + … + 47 =
  5. 5.1 + 3 + 5 + … + 45 =
  6. 6.1 + 2 + 3 + … + 6 =
  7. 7.1 + 2 + 3 + … + 69 =
  8. 8.1 + 3 + 5 + … + 35 =
  9. 9.1 + 3 + 5 + … + 43 =
  10. 10.1 + 2 + 3 + … + 9 =
  11. 11.1 + 2 + 3 + … + 84 =
  12. 12.1 + 2 + 3 + … + 82 =
  13. 13.1 + 2 + 3 + … + 31 =
  14. 14.1 + 2 + 3 + … + 62 =
  15. 15.1 + 3 + 5 + … + 21 =
  16. 16.1 + 2 + 3 + … + 71 =
  17. 17.1 + 2 + 3 + … + 36 =
  18. 18.1 + 2 + 3 + … + 81 =
  19. 19.1 + 2 + 3 + … + 47 =
  20. 20.1 + 3 + 5 + … + 39 =
  21. 21.1 + 2 + 3 + … + 44 =
  22. 22.1 + 2 + 3 + … + 70 =
  23. 23.1 + 2 + 3 + … + 14 =
  24. 24.1 + 2 + 3 + … + 52 =
  25. 25.1 + 2 + 3 + … + 38 =
  26. 26.1 + 2 + 3 + … + 100 =
  27. 27.1 + 2 + 3 + … + 56 =
  28. 28.1 + 2 + 3 + … + 75 =
  29. 29.1 + 2 + 3 + … + 30 =
  30. 30.1 + 3 + 5 + … + 37 =
  31. 31.1 + 2 + 3 + … + 19 =
  32. 32.1 + 2 + 3 + … + 11 =
  33. 33.1 + 3 + 5 + … + 11 =
  34. 34.1 + 2 + 3 + … + 25 =
  35. 35.1 + 3 + 5 + … + 15 =
  36. 36.1 + 2 + 3 + … + 68 =
  37. 37.1 + 3 + 5 + … + 31 =
  38. 38.1 + 3 + 5 + … + 23 =
  39. 39.1 + 2 + 3 + … + 96 =
  40. 40.1 + 2 + 3 + … + 91 =

Answer key

  1. 196
  2. 595
  3. 3240
  4. 576
  5. 529
  6. 21
  7. 2415
  8. 324
  9. 484
  10. 45
  11. 3570
  12. 3403
  13. 496
  14. 1953
  15. 121
  16. 2556
  17. 666
  18. 3321
  19. 1128
  20. 400
  21. 990
  22. 2485
  23. 105
  24. 1378
  25. 741
  26. 5050
  27. 1596
  28. 2850
  29. 465
  30. 361
  31. 190
  32. 66
  33. 36
  34. 325
  35. 64
  36. 2346
  37. 256
  38. 144
  39. 4656
  40. 4186

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