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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 124 · 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 + 2 + 3 + … + 15 =
  3. 3.1 + 2 + 3 + … + 29 =
  4. 4.1 + 3 + 5 + … + 17 =
  5. 5.1 + 3 + 5 + … + 9 =
  6. 6.1 + 2 + 3 + … + 19 =
  7. 7.1 + 2 + 3 + … + 42 =
  8. 8.1 + 2 + 3 + … + 18 =
  9. 9.1 + 2 + 3 + … + 7 =
  10. 10.1 + 2 + 3 + … + 27 =
  11. 11.1 + 2 + 3 + … + 8 =
  12. 12.1 + 3 + 5 + … + 23 =
  13. 13.1 + 2 + 3 + … + 25 =
  14. 14.1 + 3 + 5 + … + 41 =
  15. 15.1 + 2 + 3 + … + 34 =
  16. 16.1 + 3 + 5 + … + 15 =
  17. 17.1 + 3 + 5 + … + 13 =
  18. 18.1 + 2 + 3 + … + 23 =
  19. 19.1 + 2 + 3 + … + 62 =
  20. 20.1 + 2 + 3 + … + 98 =
  21. 21.1 + 2 + 3 + … + 59 =
  22. 22.1 + 2 + 3 + … + 40 =
  23. 23.1 + 2 + 3 + … + 31 =
  24. 24.1 + 3 + 5 + … + 37 =
  25. 25.1 + 2 + 3 + … + 37 =
  26. 26.1 + 3 + 5 + … + 25 =
  27. 27.1 + 2 + 3 + … + 56 =
  28. 28.1 + 2 + 3 + … + 57 =
  29. 29.1 + 2 + 3 + … + 6 =
  30. 30.1 + 2 + 3 + … + 91 =
  31. 31.1 + 2 + 3 + … + 61 =
  32. 32.1 + 2 + 3 + … + 86 =
  33. 33.1 + 3 + 5 + … + 35 =
  34. 34.1 + 3 + 5 + … + 27 =
  35. 35.1 + 2 + 3 + … + 13 =
  36. 36.1 + 2 + 3 + … + 48 =
  37. 37.1 + 2 + 3 + … + 49 =
  38. 38.1 + 2 + 3 + … + 21 =
  39. 39.1 + 2 + 3 + … + 67 =
  40. 40.1 + 2 + 3 + … + 73 =

Answer key

  1. 256
  2. 120
  3. 435
  4. 81
  5. 25
  6. 190
  7. 903
  8. 171
  9. 28
  10. 378
  11. 36
  12. 144
  13. 325
  14. 441
  15. 595
  16. 64
  17. 49
  18. 276
  19. 1953
  20. 4851
  21. 1770
  22. 820
  23. 496
  24. 361
  25. 703
  26. 169
  27. 1596
  28. 1653
  29. 21
  30. 4186
  31. 1891
  32. 3741
  33. 324
  34. 196
  35. 91
  36. 1176
  37. 1225
  38. 231
  39. 2278
  40. 2701

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