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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 537 · 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 + … + 8 =
  2. 2.1 + 2 + 3 + … + 91 =
  3. 3.1 + 3 + 5 + … + 21 =
  4. 4.1 + 2 + 3 + … + 93 =
  5. 5.1 + 2 + 3 + … + 79 =
  6. 6.1 + 3 + 5 + … + 37 =
  7. 7.1 + 3 + 5 + … + 33 =
  8. 8.1 + 2 + 3 + … + 62 =
  9. 9.1 + 2 + 3 + … + 50 =
  10. 10.1 + 2 + 3 + … + 61 =
  11. 11.1 + 2 + 3 + … + 20 =
  12. 12.1 + 2 + 3 + … + 31 =
  13. 13.1 + 3 + 5 + … + 15 =
  14. 14.1 + 2 + 3 + … + 15 =
  15. 15.1 + 2 + 3 + … + 46 =
  16. 16.1 + 2 + 3 + … + 14 =
  17. 17.1 + 2 + 3 + … + 12 =
  18. 18.1 + 2 + 3 + … + 84 =
  19. 19.1 + 3 + 5 + … + 23 =
  20. 20.1 + 3 + 5 + … + 9 =
  21. 21.1 + 2 + 3 + … + 9 =
  22. 22.1 + 3 + 5 + … + 17 =
  23. 23.1 + 2 + 3 + … + 23 =
  24. 24.1 + 3 + 5 + … + 19 =
  25. 25.1 + 2 + 3 + … + 26 =
  26. 26.1 + 3 + 5 + … + 13 =
  27. 27.1 + 3 + 5 + … + 43 =
  28. 28.1 + 2 + 3 + … + 73 =
  29. 29.1 + 2 + 3 + … + 42 =
  30. 30.1 + 2 + 3 + … + 49 =
  31. 31.1 + 3 + 5 + … + 11 =
  32. 32.1 + 3 + 5 + … + 25 =
  33. 33.1 + 2 + 3 + … + 71 =
  34. 34.1 + 3 + 5 + … + 27 =
  35. 35.1 + 2 + 3 + … + 41 =
  36. 36.1 + 2 + 3 + … + 75 =
  37. 37.1 + 2 + 3 + … + 96 =
  38. 38.1 + 2 + 3 + … + 87 =
  39. 39.1 + 2 + 3 + … + 99 =
  40. 40.1 + 2 + 3 + … + 38 =

Answer key

  1. 36
  2. 4186
  3. 121
  4. 4371
  5. 3160
  6. 361
  7. 289
  8. 1953
  9. 1275
  10. 1891
  11. 210
  12. 496
  13. 64
  14. 120
  15. 1081
  16. 105
  17. 78
  18. 3570
  19. 144
  20. 25
  21. 45
  22. 81
  23. 276
  24. 100
  25. 351
  26. 49
  27. 484
  28. 2701
  29. 903
  30. 1225
  31. 36
  32. 169
  33. 2556
  34. 196
  35. 861
  36. 2850
  37. 4656
  38. 3828
  39. 4950
  40. 741

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