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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 74 · 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 + … + 31 =
  2. 2.1 + 3 + 5 + … + 19 =
  3. 3.1 + 3 + 5 + … + 17 =
  4. 4.1 + 2 + 3 + … + 31 =
  5. 5.1 + 2 + 3 + … + 93 =
  6. 6.1 + 2 + 3 + … + 22 =
  7. 7.1 + 2 + 3 + … + 72 =
  8. 8.1 + 2 + 3 + … + 71 =
  9. 9.1 + 2 + 3 + … + 45 =
  10. 10.1 + 2 + 3 + … + 94 =
  11. 11.1 + 2 + 3 + … + 27 =
  12. 12.1 + 3 + 5 + … + 39 =
  13. 13.1 + 2 + 3 + … + 18 =
  14. 14.1 + 2 + 3 + … + 43 =
  15. 15.1 + 3 + 5 + … + 27 =
  16. 16.1 + 2 + 3 + … + 77 =
  17. 17.1 + 2 + 3 + … + 73 =
  18. 18.1 + 3 + 5 + … + 25 =
  19. 19.1 + 2 + 3 + … + 6 =
  20. 20.1 + 2 + 3 + … + 90 =
  21. 21.1 + 2 + 3 + … + 12 =
  22. 22.1 + 2 + 3 + … + 69 =
  23. 23.1 + 2 + 3 + … + 15 =
  24. 24.1 + 2 + 3 + … + 17 =
  25. 25.1 + 2 + 3 + … + 56 =
  26. 26.1 + 3 + 5 + … + 35 =
  27. 27.1 + 2 + 3 + … + 68 =
  28. 28.1 + 2 + 3 + … + 23 =
  29. 29.1 + 2 + 3 + … + 82 =
  30. 30.1 + 2 + 3 + … + 86 =
  31. 31.1 + 2 + 3 + … + 7 =
  32. 32.1 + 2 + 3 + … + 60 =
  33. 33.1 + 2 + 3 + … + 11 =
  34. 34.1 + 2 + 3 + … + 42 =
  35. 35.1 + 3 + 5 + … + 21 =
  36. 36.1 + 2 + 3 + … + 53 =
  37. 37.1 + 3 + 5 + … + 15 =
  38. 38.1 + 2 + 3 + … + 91 =
  39. 39.1 + 2 + 3 + … + 76 =
  40. 40.1 + 2 + 3 + … + 55 =

Answer key

  1. 256
  2. 100
  3. 81
  4. 496
  5. 4371
  6. 253
  7. 2628
  8. 2556
  9. 1035
  10. 4465
  11. 378
  12. 400
  13. 171
  14. 946
  15. 196
  16. 3003
  17. 2701
  18. 169
  19. 21
  20. 4095
  21. 78
  22. 2415
  23. 120
  24. 153
  25. 1596
  26. 324
  27. 2346
  28. 276
  29. 3403
  30. 3741
  31. 28
  32. 1830
  33. 66
  34. 903
  35. 121
  36. 1431
  37. 64
  38. 4186
  39. 2926
  40. 1540

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