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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 478 · 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 + … + 13 =
  2. 2.1 + 3 + 5 + … + 9 =
  3. 3.1 + 3 + 5 + … + 11 =
  4. 4.1 + 3 + 5 + … + 23 =
  5. 5.1 + 2 + 3 + … + 56 =
  6. 6.1 + 3 + 5 + … + 27 =
  7. 7.1 + 3 + 5 + … + 45 =
  8. 8.1 + 2 + 3 + … + 70 =
  9. 9.1 + 3 + 5 + … + 41 =
  10. 10.1 + 2 + 3 + … + 78 =
  11. 11.1 + 2 + 3 + … + 77 =
  12. 12.1 + 2 + 3 + … + 98 =
  13. 13.1 + 3 + 5 + … + 47 =
  14. 14.1 + 2 + 3 + … + 10 =
  15. 15.1 + 2 + 3 + … + 53 =
  16. 16.1 + 2 + 3 + … + 36 =
  17. 17.1 + 3 + 5 + … + 39 =
  18. 18.1 + 2 + 3 + … + 15 =
  19. 19.1 + 2 + 3 + … + 81 =
  20. 20.1 + 3 + 5 + … + 17 =
  21. 21.1 + 2 + 3 + … + 45 =
  22. 22.1 + 2 + 3 + … + 61 =
  23. 23.1 + 2 + 3 + … + 73 =
  24. 24.1 + 2 + 3 + … + 41 =
  25. 25.1 + 2 + 3 + … + 25 =
  26. 26.1 + 3 + 5 + … + 33 =
  27. 27.1 + 2 + 3 + … + 6 =
  28. 28.1 + 2 + 3 + … + 44 =
  29. 29.1 + 2 + 3 + … + 66 =
  30. 30.1 + 3 + 5 + … + 49 =
  31. 31.1 + 2 + 3 + … + 68 =
  32. 32.1 + 2 + 3 + … + 83 =
  33. 33.1 + 2 + 3 + … + 29 =
  34. 34.1 + 2 + 3 + … + 87 =
  35. 35.1 + 2 + 3 + … + 97 =
  36. 36.1 + 2 + 3 + … + 12 =
  37. 37.1 + 2 + 3 + … + 19 =
  38. 38.1 + 2 + 3 + … + 42 =
  39. 39.1 + 2 + 3 + … + 27 =
  40. 40.1 + 2 + 3 + … + 67 =

Answer key

  1. 49
  2. 25
  3. 36
  4. 144
  5. 1596
  6. 196
  7. 529
  8. 2485
  9. 441
  10. 3081
  11. 3003
  12. 4851
  13. 576
  14. 55
  15. 1431
  16. 666
  17. 400
  18. 120
  19. 3321
  20. 81
  21. 1035
  22. 1891
  23. 2701
  24. 861
  25. 325
  26. 289
  27. 21
  28. 990
  29. 2211
  30. 625
  31. 2346
  32. 3486
  33. 435
  34. 3828
  35. 4753
  36. 78
  37. 190
  38. 903
  39. 378
  40. 2278

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