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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 750 · 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 + … + 98 =
  2. 2.1 + 3 + 5 + … + 19 =
  3. 3.1 + 2 + 3 + … + 50 =
  4. 4.1 + 3 + 5 + … + 37 =
  5. 5.1 + 3 + 5 + … + 21 =
  6. 6.1 + 2 + 3 + … + 52 =
  7. 7.1 + 2 + 3 + … + 30 =
  8. 8.1 + 2 + 3 + … + 31 =
  9. 9.1 + 2 + 3 + … + 94 =
  10. 10.1 + 2 + 3 + … + 13 =
  11. 11.1 + 2 + 3 + … + 41 =
  12. 12.1 + 2 + 3 + … + 66 =
  13. 13.1 + 2 + 3 + … + 22 =
  14. 14.1 + 2 + 3 + … + 42 =
  15. 15.1 + 3 + 5 + … + 15 =
  16. 16.1 + 3 + 5 + … + 11 =
  17. 17.1 + 3 + 5 + … + 17 =
  18. 18.1 + 2 + 3 + … + 71 =
  19. 19.1 + 2 + 3 + … + 12 =
  20. 20.1 + 3 + 5 + … + 25 =
  21. 21.1 + 3 + 5 + … + 41 =
  22. 22.1 + 2 + 3 + … + 36 =
  23. 23.1 + 2 + 3 + … + 14 =
  24. 24.1 + 2 + 3 + … + 17 =
  25. 25.1 + 2 + 3 + … + 38 =
  26. 26.1 + 3 + 5 + … + 43 =
  27. 27.1 + 3 + 5 + … + 29 =
  28. 28.1 + 3 + 5 + … + 23 =
  29. 29.1 + 3 + 5 + … + 13 =
  30. 30.1 + 2 + 3 + … + 8 =
  31. 31.1 + 2 + 3 + … + 84 =
  32. 32.1 + 2 + 3 + … + 51 =
  33. 33.1 + 2 + 3 + … + 46 =
  34. 34.1 + 2 + 3 + … + 20 =
  35. 35.1 + 2 + 3 + … + 55 =
  36. 36.1 + 2 + 3 + … + 92 =
  37. 37.1 + 3 + 5 + … + 35 =
  38. 38.1 + 2 + 3 + … + 37 =
  39. 39.1 + 2 + 3 + … + 64 =
  40. 40.1 + 2 + 3 + … + 63 =

Answer key

  1. 4851
  2. 100
  3. 1275
  4. 361
  5. 121
  6. 1378
  7. 465
  8. 496
  9. 4465
  10. 91
  11. 861
  12. 2211
  13. 253
  14. 903
  15. 64
  16. 36
  17. 81
  18. 2556
  19. 78
  20. 169
  21. 441
  22. 666
  23. 105
  24. 153
  25. 741
  26. 484
  27. 225
  28. 144
  29. 49
  30. 36
  31. 3570
  32. 1326
  33. 1081
  34. 210
  35. 1540
  36. 4278
  37. 324
  38. 703
  39. 2080
  40. 2016

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