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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 612 · 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 + … + 23 =
  2. 2.1 + 3 + 5 + … + 47 =
  3. 3.1 + 3 + 5 + … + 25 =
  4. 4.1 + 2 + 3 + … + 49 =
  5. 5.1 + 3 + 5 + … + 21 =
  6. 6.1 + 2 + 3 + … + 46 =
  7. 7.1 + 3 + 5 + … + 9 =
  8. 8.1 + 2 + 3 + … + 8 =
  9. 9.1 + 3 + 5 + … + 13 =
  10. 10.1 + 3 + 5 + … + 39 =
  11. 11.1 + 3 + 5 + … + 11 =
  12. 12.1 + 2 + 3 + … + 67 =
  13. 13.1 + 2 + 3 + … + 90 =
  14. 14.1 + 2 + 3 + … + 71 =
  15. 15.1 + 2 + 3 + … + 88 =
  16. 16.1 + 2 + 3 + … + 84 =
  17. 17.1 + 2 + 3 + … + 98 =
  18. 18.1 + 2 + 3 + … + 73 =
  19. 19.1 + 2 + 3 + … + 37 =
  20. 20.1 + 3 + 5 + … + 29 =
  21. 21.1 + 2 + 3 + … + 96 =
  22. 22.1 + 2 + 3 + … + 59 =
  23. 23.1 + 2 + 3 + … + 31 =
  24. 24.1 + 2 + 3 + … + 92 =
  25. 25.1 + 3 + 5 + … + 15 =
  26. 26.1 + 3 + 5 + … + 17 =
  27. 27.1 + 2 + 3 + … + 63 =
  28. 28.1 + 2 + 3 + … + 44 =
  29. 29.1 + 2 + 3 + … + 14 =
  30. 30.1 + 2 + 3 + … + 38 =
  31. 31.1 + 2 + 3 + … + 32 =
  32. 32.1 + 2 + 3 + … + 6 =
  33. 33.1 + 3 + 5 + … + 43 =
  34. 34.1 + 2 + 3 + … + 21 =
  35. 35.1 + 2 + 3 + … + 22 =
  36. 36.1 + 2 + 3 + … + 82 =
  37. 37.1 + 2 + 3 + … + 40 =
  38. 38.1 + 2 + 3 + … + 9 =
  39. 39.1 + 2 + 3 + … + 42 =
  40. 40.1 + 3 + 5 + … + 35 =

Answer key

  1. 276
  2. 576
  3. 169
  4. 1225
  5. 121
  6. 1081
  7. 25
  8. 36
  9. 49
  10. 400
  11. 36
  12. 2278
  13. 4095
  14. 2556
  15. 3916
  16. 3570
  17. 4851
  18. 2701
  19. 703
  20. 225
  21. 4656
  22. 1770
  23. 496
  24. 4278
  25. 64
  26. 81
  27. 2016
  28. 990
  29. 105
  30. 741
  31. 528
  32. 21
  33. 484
  34. 231
  35. 253
  36. 3403
  37. 820
  38. 45
  39. 903
  40. 324

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