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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 515 · 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 + … + 8 =
  2. 2.1 + 2 + 3 + … + 25 =
  3. 3.1 + 3 + 5 + … + 17 =
  4. 4.1 + 2 + 3 + … + 81 =
  5. 5.1 + 2 + 3 + … + 23 =
  6. 6.1 + 2 + 3 + … + 62 =
  7. 7.1 + 2 + 3 + … + 95 =
  8. 8.1 + 2 + 3 + … + 42 =
  9. 9.1 + 2 + 3 + … + 30 =
  10. 10.1 + 2 + 3 + … + 44 =
  11. 11.1 + 2 + 3 + … + 11 =
  12. 12.1 + 3 + 5 + … + 33 =
  13. 13.1 + 2 + 3 + … + 27 =
  14. 14.1 + 2 + 3 + … + 96 =
  15. 15.1 + 3 + 5 + … + 27 =
  16. 16.1 + 2 + 3 + … + 53 =
  17. 17.1 + 2 + 3 + … + 59 =
  18. 18.1 + 2 + 3 + … + 76 =
  19. 19.1 + 2 + 3 + … + 98 =
  20. 20.1 + 2 + 3 + … + 9 =
  21. 21.1 + 2 + 3 + … + 14 =
  22. 22.1 + 2 + 3 + … + 94 =
  23. 23.1 + 3 + 5 + … + 29 =
  24. 24.1 + 3 + 5 + … + 21 =
  25. 25.1 + 2 + 3 + … + 84 =
  26. 26.1 + 3 + 5 + … + 9 =
  27. 27.1 + 2 + 3 + … + 51 =
  28. 28.1 + 2 + 3 + … + 36 =
  29. 29.1 + 3 + 5 + … + 15 =
  30. 30.1 + 2 + 3 + … + 50 =
  31. 31.1 + 2 + 3 + … + 99 =
  32. 32.1 + 2 + 3 + … + 15 =
  33. 33.1 + 2 + 3 + … + 72 =
  34. 34.1 + 2 + 3 + … + 17 =
  35. 35.1 + 2 + 3 + … + 47 =
  36. 36.1 + 2 + 3 + … + 18 =
  37. 37.1 + 2 + 3 + … + 85 =
  38. 38.1 + 2 + 3 + … + 46 =
  39. 39.1 + 2 + 3 + … + 43 =
  40. 40.1 + 2 + 3 + … + 66 =

Answer key

  1. 36
  2. 325
  3. 81
  4. 3321
  5. 276
  6. 1953
  7. 4560
  8. 903
  9. 465
  10. 990
  11. 66
  12. 289
  13. 378
  14. 4656
  15. 196
  16. 1431
  17. 1770
  18. 2926
  19. 4851
  20. 45
  21. 105
  22. 4465
  23. 225
  24. 121
  25. 3570
  26. 25
  27. 1326
  28. 666
  29. 64
  30. 1275
  31. 4950
  32. 120
  33. 2628
  34. 153
  35. 1128
  36. 171
  37. 3655
  38. 1081
  39. 946
  40. 2211

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