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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 954 · 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 + … + 66 =
  2. 2.1 + 2 + 3 + … + 28 =
  3. 3.1 + 2 + 3 + … + 73 =
  4. 4.1 + 3 + 5 + … + 45 =
  5. 5.1 + 2 + 3 + … + 25 =
  6. 6.1 + 2 + 3 + … + 51 =
  7. 7.1 + 3 + 5 + … + 13 =
  8. 8.1 + 2 + 3 + … + 91 =
  9. 9.1 + 3 + 5 + … + 21 =
  10. 10.1 + 2 + 3 + … + 80 =
  11. 11.1 + 2 + 3 + … + 71 =
  12. 12.1 + 2 + 3 + … + 47 =
  13. 13.1 + 2 + 3 + … + 88 =
  14. 14.1 + 2 + 3 + … + 10 =
  15. 15.1 + 2 + 3 + … + 14 =
  16. 16.1 + 2 + 3 + … + 27 =
  17. 17.1 + 2 + 3 + … + 52 =
  18. 18.1 + 3 + 5 + … + 23 =
  19. 19.1 + 3 + 5 + … + 35 =
  20. 20.1 + 2 + 3 + … + 89 =
  21. 21.1 + 2 + 3 + … + 53 =
  22. 22.1 + 2 + 3 + … + 38 =
  23. 23.1 + 2 + 3 + … + 57 =
  24. 24.1 + 2 + 3 + … + 84 =
  25. 25.1 + 2 + 3 + … + 76 =
  26. 26.1 + 2 + 3 + … + 100 =
  27. 27.1 + 3 + 5 + … + 41 =
  28. 28.1 + 3 + 5 + … + 27 =
  29. 29.1 + 3 + 5 + … + 17 =
  30. 30.1 + 2 + 3 + … + 69 =
  31. 31.1 + 2 + 3 + … + 50 =
  32. 32.1 + 2 + 3 + … + 74 =
  33. 33.1 + 2 + 3 + … + 43 =
  34. 34.1 + 2 + 3 + … + 9 =
  35. 35.1 + 3 + 5 + … + 15 =
  36. 36.1 + 2 + 3 + … + 77 =
  37. 37.1 + 2 + 3 + … + 31 =
  38. 38.1 + 2 + 3 + … + 18 =
  39. 39.1 + 2 + 3 + … + 92 =
  40. 40.1 + 2 + 3 + … + 8 =

Answer key

  1. 2211
  2. 406
  3. 2701
  4. 529
  5. 325
  6. 1326
  7. 49
  8. 4186
  9. 121
  10. 3240
  11. 2556
  12. 1128
  13. 3916
  14. 55
  15. 105
  16. 378
  17. 1378
  18. 144
  19. 324
  20. 4005
  21. 1431
  22. 741
  23. 1653
  24. 3570
  25. 2926
  26. 5050
  27. 441
  28. 196
  29. 81
  30. 2415
  31. 1275
  32. 2775
  33. 946
  34. 45
  35. 64
  36. 3003
  37. 496
  38. 171
  39. 4278
  40. 36

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