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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 139 · 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 + … + 39 =
  2. 2.1 + 2 + 3 + … + 99 =
  3. 3.1 + 2 + 3 + … + 15 =
  4. 4.1 + 2 + 3 + … + 9 =
  5. 5.1 + 3 + 5 + … + 31 =
  6. 6.1 + 3 + 5 + … + 43 =
  7. 7.1 + 2 + 3 + … + 20 =
  8. 8.1 + 3 + 5 + … + 23 =
  9. 9.1 + 2 + 3 + … + 39 =
  10. 10.1 + 2 + 3 + … + 91 =
  11. 11.1 + 2 + 3 + … + 19 =
  12. 12.1 + 2 + 3 + … + 38 =
  13. 13.1 + 2 + 3 + … + 13 =
  14. 14.1 + 3 + 5 + … + 19 =
  15. 15.1 + 3 + 5 + … + 41 =
  16. 16.1 + 2 + 3 + … + 78 =
  17. 17.1 + 3 + 5 + … + 15 =
  18. 18.1 + 2 + 3 + … + 59 =
  19. 19.1 + 2 + 3 + … + 90 =
  20. 20.1 + 2 + 3 + … + 73 =
  21. 21.1 + 2 + 3 + … + 96 =
  22. 22.1 + 2 + 3 + … + 60 =
  23. 23.1 + 2 + 3 + … + 26 =
  24. 24.1 + 3 + 5 + … + 29 =
  25. 25.1 + 2 + 3 + … + 50 =
  26. 26.1 + 2 + 3 + … + 88 =
  27. 27.1 + 2 + 3 + … + 65 =
  28. 28.1 + 2 + 3 + … + 92 =
  29. 29.1 + 2 + 3 + … + 28 =
  30. 30.1 + 2 + 3 + … + 95 =
  31. 31.1 + 3 + 5 + … + 17 =
  32. 32.1 + 3 + 5 + … + 9 =
  33. 33.1 + 2 + 3 + … + 75 =
  34. 34.1 + 2 + 3 + … + 54 =
  35. 35.1 + 2 + 3 + … + 63 =
  36. 36.1 + 2 + 3 + … + 16 =
  37. 37.1 + 2 + 3 + … + 80 =
  38. 38.1 + 2 + 3 + … + 22 =
  39. 39.1 + 2 + 3 + … + 56 =
  40. 40.1 + 2 + 3 + … + 46 =

Answer key

  1. 400
  2. 4950
  3. 120
  4. 45
  5. 256
  6. 484
  7. 210
  8. 144
  9. 780
  10. 4186
  11. 190
  12. 741
  13. 91
  14. 100
  15. 441
  16. 3081
  17. 64
  18. 1770
  19. 4095
  20. 2701
  21. 4656
  22. 1830
  23. 351
  24. 225
  25. 1275
  26. 3916
  27. 2145
  28. 4278
  29. 406
  30. 4560
  31. 81
  32. 25
  33. 2850
  34. 1485
  35. 2016
  36. 136
  37. 3240
  38. 253
  39. 1596
  40. 1081

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