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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 866 · 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 + … + 12 =
  2. 2.1 + 2 + 3 + … + 32 =
  3. 3.1 + 2 + 3 + … + 26 =
  4. 4.1 + 3 + 5 + … + 29 =
  5. 5.1 + 2 + 3 + … + 10 =
  6. 6.1 + 2 + 3 + … + 7 =
  7. 7.1 + 3 + 5 + … + 33 =
  8. 8.1 + 3 + 5 + … + 11 =
  9. 9.1 + 2 + 3 + … + 14 =
  10. 10.1 + 2 + 3 + … + 52 =
  11. 11.1 + 2 + 3 + … + 96 =
  12. 12.1 + 2 + 3 + … + 8 =
  13. 13.1 + 3 + 5 + … + 37 =
  14. 14.1 + 2 + 3 + … + 20 =
  15. 15.1 + 2 + 3 + … + 92 =
  16. 16.1 + 2 + 3 + … + 55 =
  17. 17.1 + 2 + 3 + … + 64 =
  18. 18.1 + 3 + 5 + … + 31 =
  19. 19.1 + 2 + 3 + … + 94 =
  20. 20.1 + 3 + 5 + … + 23 =
  21. 21.1 + 3 + 5 + … + 39 =
  22. 22.1 + 3 + 5 + … + 9 =
  23. 23.1 + 2 + 3 + … + 23 =
  24. 24.1 + 2 + 3 + … + 43 =
  25. 25.1 + 2 + 3 + … + 42 =
  26. 26.1 + 2 + 3 + … + 15 =
  27. 27.1 + 3 + 5 + … + 47 =
  28. 28.1 + 2 + 3 + … + 45 =
  29. 29.1 + 2 + 3 + … + 44 =
  30. 30.1 + 2 + 3 + … + 93 =
  31. 31.1 + 2 + 3 + … + 69 =
  32. 32.1 + 2 + 3 + … + 9 =
  33. 33.1 + 2 + 3 + … + 51 =
  34. 34.1 + 2 + 3 + … + 6 =
  35. 35.1 + 2 + 3 + … + 37 =
  36. 36.1 + 2 + 3 + … + 84 =
  37. 37.1 + 3 + 5 + … + 15 =
  38. 38.1 + 2 + 3 + … + 29 =
  39. 39.1 + 3 + 5 + … + 19 =
  40. 40.1 + 2 + 3 + … + 99 =

Answer key

  1. 78
  2. 528
  3. 351
  4. 225
  5. 55
  6. 28
  7. 289
  8. 36
  9. 105
  10. 1378
  11. 4656
  12. 36
  13. 361
  14. 210
  15. 4278
  16. 1540
  17. 2080
  18. 256
  19. 4465
  20. 144
  21. 400
  22. 25
  23. 276
  24. 946
  25. 903
  26. 120
  27. 576
  28. 1035
  29. 990
  30. 4371
  31. 2415
  32. 45
  33. 1326
  34. 21
  35. 703
  36. 3570
  37. 64
  38. 435
  39. 100
  40. 4950

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