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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 964 · 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 + … + 21 =
  2. 2.1 + 3 + 5 + … + 23 =
  3. 3.1 + 2 + 3 + … + 33 =
  4. 4.1 + 3 + 5 + … + 31 =
  5. 5.1 + 3 + 5 + … + 45 =
  6. 6.1 + 2 + 3 + … + 93 =
  7. 7.1 + 2 + 3 + … + 97 =
  8. 8.1 + 2 + 3 + … + 11 =
  9. 9.1 + 2 + 3 + … + 30 =
  10. 10.1 + 3 + 5 + … + 25 =
  11. 11.1 + 3 + 5 + … + 13 =
  12. 12.1 + 2 + 3 + … + 94 =
  13. 13.1 + 2 + 3 + … + 89 =
  14. 14.1 + 2 + 3 + … + 75 =
  15. 15.1 + 2 + 3 + … + 52 =
  16. 16.1 + 3 + 5 + … + 15 =
  17. 17.1 + 2 + 3 + … + 46 =
  18. 18.1 + 2 + 3 + … + 15 =
  19. 19.1 + 2 + 3 + … + 81 =
  20. 20.1 + 2 + 3 + … + 36 =
  21. 21.1 + 2 + 3 + … + 38 =
  22. 22.1 + 2 + 3 + … + 71 =
  23. 23.1 + 2 + 3 + … + 64 =
  24. 24.1 + 2 + 3 + … + 63 =
  25. 25.1 + 3 + 5 + … + 43 =
  26. 26.1 + 2 + 3 + … + 32 =
  27. 27.1 + 3 + 5 + … + 41 =
  28. 28.1 + 2 + 3 + … + 44 =
  29. 29.1 + 3 + 5 + … + 11 =
  30. 30.1 + 2 + 3 + … + 66 =
  31. 31.1 + 2 + 3 + … + 73 =
  32. 32.1 + 2 + 3 + … + 20 =
  33. 33.1 + 2 + 3 + … + 69 =
  34. 34.1 + 2 + 3 + … + 72 =
  35. 35.1 + 2 + 3 + … + 39 =
  36. 36.1 + 2 + 3 + … + 55 =
  37. 37.1 + 3 + 5 + … + 33 =
  38. 38.1 + 2 + 3 + … + 42 =
  39. 39.1 + 3 + 5 + … + 9 =
  40. 40.1 + 2 + 3 + … + 51 =

Answer key

  1. 121
  2. 144
  3. 561
  4. 256
  5. 529
  6. 4371
  7. 4753
  8. 66
  9. 465
  10. 169
  11. 49
  12. 4465
  13. 4005
  14. 2850
  15. 1378
  16. 64
  17. 1081
  18. 120
  19. 3321
  20. 666
  21. 741
  22. 2556
  23. 2080
  24. 2016
  25. 484
  26. 528
  27. 441
  28. 990
  29. 36
  30. 2211
  31. 2701
  32. 210
  33. 2415
  34. 2628
  35. 780
  36. 1540
  37. 289
  38. 903
  39. 25
  40. 1326

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