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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 315 · 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 + … + 51 =
  2. 2.1 + 2 + 3 + … + 15 =
  3. 3.1 + 3 + 5 + … + 19 =
  4. 4.1 + 2 + 3 + … + 94 =
  5. 5.1 + 2 + 3 + … + 20 =
  6. 6.1 + 2 + 3 + … + 77 =
  7. 7.1 + 2 + 3 + … + 10 =
  8. 8.1 + 3 + 5 + … + 27 =
  9. 9.1 + 2 + 3 + … + 65 =
  10. 10.1 + 2 + 3 + … + 27 =
  11. 11.1 + 2 + 3 + … + 14 =
  12. 12.1 + 3 + 5 + … + 17 =
  13. 13.1 + 2 + 3 + … + 43 =
  14. 14.1 + 2 + 3 + … + 46 =
  15. 15.1 + 3 + 5 + … + 21 =
  16. 16.1 + 2 + 3 + … + 84 =
  17. 17.1 + 2 + 3 + … + 83 =
  18. 18.1 + 2 + 3 + … + 55 =
  19. 19.1 + 2 + 3 + … + 8 =
  20. 20.1 + 2 + 3 + … + 45 =
  21. 21.1 + 2 + 3 + … + 49 =
  22. 22.1 + 3 + 5 + … + 31 =
  23. 23.1 + 2 + 3 + … + 29 =
  24. 24.1 + 2 + 3 + … + 13 =
  25. 25.1 + 3 + 5 + … + 15 =
  26. 26.1 + 2 + 3 + … + 56 =
  27. 27.1 + 2 + 3 + … + 48 =
  28. 28.1 + 3 + 5 + … + 37 =
  29. 29.1 + 3 + 5 + … + 9 =
  30. 30.1 + 2 + 3 + … + 16 =
  31. 31.1 + 2 + 3 + … + 62 =
  32. 32.1 + 2 + 3 + … + 30 =
  33. 33.1 + 3 + 5 + … + 23 =
  34. 34.1 + 3 + 5 + … + 29 =
  35. 35.1 + 2 + 3 + … + 86 =
  36. 36.1 + 2 + 3 + … + 76 =
  37. 37.1 + 2 + 3 + … + 70 =
  38. 38.1 + 2 + 3 + … + 39 =
  39. 39.1 + 2 + 3 + … + 52 =
  40. 40.1 + 2 + 3 + … + 96 =

Answer key

  1. 1326
  2. 120
  3. 100
  4. 4465
  5. 210
  6. 3003
  7. 55
  8. 196
  9. 2145
  10. 378
  11. 105
  12. 81
  13. 946
  14. 1081
  15. 121
  16. 3570
  17. 3486
  18. 1540
  19. 36
  20. 1035
  21. 1225
  22. 256
  23. 435
  24. 91
  25. 64
  26. 1596
  27. 1176
  28. 361
  29. 25
  30. 136
  31. 1953
  32. 465
  33. 144
  34. 225
  35. 3741
  36. 2926
  37. 2485
  38. 780
  39. 1378
  40. 4656

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