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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 62 · 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 + … + 33 =
  2. 2.1 + 2 + 3 + … + 53 =
  3. 3.1 + 2 + 3 + … + 33 =
  4. 4.1 + 2 + 3 + … + 13 =
  5. 5.1 + 2 + 3 + … + 92 =
  6. 6.1 + 3 + 5 + … + 11 =
  7. 7.1 + 3 + 5 + … + 19 =
  8. 8.1 + 2 + 3 + … + 7 =
  9. 9.1 + 2 + 3 + … + 16 =
  10. 10.1 + 3 + 5 + … + 43 =
  11. 11.1 + 2 + 3 + … + 73 =
  12. 12.1 + 2 + 3 + … + 14 =
  13. 13.1 + 2 + 3 + … + 72 =
  14. 14.1 + 3 + 5 + … + 39 =
  15. 15.1 + 3 + 5 + … + 41 =
  16. 16.1 + 2 + 3 + … + 30 =
  17. 17.1 + 2 + 3 + … + 100 =
  18. 18.1 + 3 + 5 + … + 31 =
  19. 19.1 + 2 + 3 + … + 88 =
  20. 20.1 + 3 + 5 + … + 9 =
  21. 21.1 + 2 + 3 + … + 19 =
  22. 22.1 + 2 + 3 + … + 67 =
  23. 23.1 + 2 + 3 + … + 66 =
  24. 24.1 + 2 + 3 + … + 38 =
  25. 25.1 + 3 + 5 + … + 37 =
  26. 26.1 + 2 + 3 + … + 10 =
  27. 27.1 + 2 + 3 + … + 78 =
  28. 28.1 + 2 + 3 + … + 75 =
  29. 29.1 + 2 + 3 + … + 8 =
  30. 30.1 + 2 + 3 + … + 98 =
  31. 31.1 + 2 + 3 + … + 79 =
  32. 32.1 + 2 + 3 + … + 11 =
  33. 33.1 + 3 + 5 + … + 35 =
  34. 34.1 + 3 + 5 + … + 45 =
  35. 35.1 + 2 + 3 + … + 36 =
  36. 36.1 + 2 + 3 + … + 86 =
  37. 37.1 + 2 + 3 + … + 22 =
  38. 38.1 + 2 + 3 + … + 6 =
  39. 39.1 + 2 + 3 + … + 60 =
  40. 40.1 + 3 + 5 + … + 23 =

Answer key

  1. 289
  2. 1431
  3. 561
  4. 91
  5. 4278
  6. 36
  7. 100
  8. 28
  9. 136
  10. 484
  11. 2701
  12. 105
  13. 2628
  14. 400
  15. 441
  16. 465
  17. 5050
  18. 256
  19. 3916
  20. 25
  21. 190
  22. 2278
  23. 2211
  24. 741
  25. 361
  26. 55
  27. 3081
  28. 2850
  29. 36
  30. 4851
  31. 3160
  32. 66
  33. 324
  34. 529
  35. 666
  36. 3741
  37. 253
  38. 21
  39. 1830
  40. 144

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