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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 911 · 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 + … + 61 =
  2. 2.1 + 2 + 3 + … + 17 =
  3. 3.1 + 2 + 3 + … + 52 =
  4. 4.1 + 3 + 5 + … + 13 =
  5. 5.1 + 2 + 3 + … + 27 =
  6. 6.1 + 2 + 3 + … + 53 =
  7. 7.1 + 3 + 5 + … + 15 =
  8. 8.1 + 2 + 3 + … + 46 =
  9. 9.1 + 2 + 3 + … + 68 =
  10. 10.1 + 2 + 3 + … + 73 =
  11. 11.1 + 3 + 5 + … + 49 =
  12. 12.1 + 2 + 3 + … + 11 =
  13. 13.1 + 2 + 3 + … + 93 =
  14. 14.1 + 3 + 5 + … + 35 =
  15. 15.1 + 2 + 3 + … + 24 =
  16. 16.1 + 2 + 3 + … + 82 =
  17. 17.1 + 2 + 3 + … + 75 =
  18. 18.1 + 2 + 3 + … + 98 =
  19. 19.1 + 2 + 3 + … + 59 =
  20. 20.1 + 2 + 3 + … + 39 =
  21. 21.1 + 2 + 3 + … + 20 =
  22. 22.1 + 2 + 3 + … + 9 =
  23. 23.1 + 2 + 3 + … + 42 =
  24. 24.1 + 3 + 5 + … + 43 =
  25. 25.1 + 2 + 3 + … + 77 =
  26. 26.1 + 3 + 5 + … + 17 =
  27. 27.1 + 2 + 3 + … + 100 =
  28. 28.1 + 2 + 3 + … + 29 =
  29. 29.1 + 2 + 3 + … + 86 =
  30. 30.1 + 2 + 3 + … + 37 =
  31. 31.1 + 2 + 3 + … + 89 =
  32. 32.1 + 2 + 3 + … + 95 =
  33. 33.1 + 2 + 3 + … + 50 =
  34. 34.1 + 2 + 3 + … + 36 =
  35. 35.1 + 2 + 3 + … + 90 =
  36. 36.1 + 2 + 3 + … + 26 =
  37. 37.1 + 2 + 3 + … + 78 =
  38. 38.1 + 3 + 5 + … + 41 =
  39. 39.1 + 2 + 3 + … + 60 =
  40. 40.1 + 2 + 3 + … + 33 =

Answer key

  1. 1891
  2. 153
  3. 1378
  4. 49
  5. 378
  6. 1431
  7. 64
  8. 1081
  9. 2346
  10. 2701
  11. 625
  12. 66
  13. 4371
  14. 324
  15. 300
  16. 3403
  17. 2850
  18. 4851
  19. 1770
  20. 780
  21. 210
  22. 45
  23. 903
  24. 484
  25. 3003
  26. 81
  27. 5050
  28. 435
  29. 3741
  30. 703
  31. 4005
  32. 4560
  33. 1275
  34. 666
  35. 4095
  36. 351
  37. 3081
  38. 441
  39. 1830
  40. 561

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