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Suppose you want to generate a password using ASCII characters ($128$ characters.)How many ways can you create a password of 10 characters long that has at least one lowercase letter (a-z) and at least one number ($0-9$)?

** MY ANSWER: $26*10*(128)^{10}$**

I don't understand why this is wrong? Can anybody help? Thanks!

  • 3
    Your answer is the amount of passwords you could generate that starts with a lower case letter, followed by a number, followed by 10 other ASCII characters. So, it's a string of length 12, and you don't take into consideration the different permutations.2012-12-17
  • 2
    ASCII characters 0 through 31 are control characters, so for practicality you would never use these in a password. Same goes for 127, the delete character. And character 32 is the space character, which is questionable in a password. So if this is not just an exercise, you might want to limit your available characters to 94 0r 95.2012-12-17

2 Answers 2