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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 425 · 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 + … + 60 =
  2. 2.1 + 2 + 3 + … + 71 =
  3. 3.1 + 2 + 3 + … + 49 =
  4. 4.1 + 3 + 5 + … + 17 =
  5. 5.1 + 2 + 3 + … + 50 =
  6. 6.1 + 3 + 5 + … + 35 =
  7. 7.1 + 2 + 3 + … + 80 =
  8. 8.1 + 3 + 5 + … + 9 =
  9. 9.1 + 2 + 3 + … + 86 =
  10. 10.1 + 3 + 5 + … + 27 =
  11. 11.1 + 3 + 5 + … + 31 =
  12. 12.1 + 2 + 3 + … + 85 =
  13. 13.1 + 2 + 3 + … + 65 =
  14. 14.1 + 3 + 5 + … + 11 =
  15. 15.1 + 2 + 3 + … + 57 =
  16. 16.1 + 2 + 3 + … + 51 =
  17. 17.1 + 2 + 3 + … + 54 =
  18. 18.1 + 2 + 3 + … + 100 =
  19. 19.1 + 2 + 3 + … + 32 =
  20. 20.1 + 3 + 5 + … + 43 =
  21. 21.1 + 2 + 3 + … + 66 =
  22. 22.1 + 2 + 3 + … + 21 =
  23. 23.1 + 3 + 5 + … + 21 =
  24. 24.1 + 2 + 3 + … + 96 =
  25. 25.1 + 2 + 3 + … + 92 =
  26. 26.1 + 2 + 3 + … + 82 =
  27. 27.1 + 2 + 3 + … + 25 =
  28. 28.1 + 3 + 5 + … + 23 =
  29. 29.1 + 2 + 3 + … + 99 =
  30. 30.1 + 2 + 3 + … + 20 =
  31. 31.1 + 2 + 3 + … + 35 =
  32. 32.1 + 2 + 3 + … + 94 =
  33. 33.1 + 3 + 5 + … + 45 =
  34. 34.1 + 2 + 3 + … + 90 =
  35. 35.1 + 2 + 3 + … + 19 =
  36. 36.1 + 2 + 3 + … + 18 =
  37. 37.1 + 2 + 3 + … + 29 =
  38. 38.1 + 2 + 3 + … + 17 =
  39. 39.1 + 2 + 3 + … + 8 =
  40. 40.1 + 3 + 5 + … + 13 =

Answer key

  1. 1830
  2. 2556
  3. 1225
  4. 81
  5. 1275
  6. 324
  7. 3240
  8. 25
  9. 3741
  10. 196
  11. 256
  12. 3655
  13. 2145
  14. 36
  15. 1653
  16. 1326
  17. 1485
  18. 5050
  19. 528
  20. 484
  21. 2211
  22. 231
  23. 121
  24. 4656
  25. 4278
  26. 3403
  27. 325
  28. 144
  29. 4950
  30. 210
  31. 630
  32. 4465
  33. 529
  34. 4095
  35. 190
  36. 171
  37. 435
  38. 153
  39. 36
  40. 49

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