# password help

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• March 24th, 2002, 06:19 AM
dieterle81
password help
i have a question about how many different passwords are possible if a password is at most
five characters long ?
the system makes no distinction between case-sensitiv and you have only 15 characters to construct a password.
thanks for the help!

cheers,
• March 24th, 2002, 06:23 AM
The3ntropy
759,375,
This answer is figued out by putting the possibilities into fractions. 1/15 chance for every character space. Five characters accounts to 1/15*1/15*1/15*1/15*1/15 and if you know how to multiply fractions the answer is 1/759375. In other words, good luck guessing, which is what I bet you were going to do.
• March 24th, 2002, 06:34 AM
tchateh
It is going to be hell working out ALL the probabilities.....if you have to
• March 24th, 2002, 07:00 AM
The3ntropy
Quoted from a PM I sent to dieterle81 explaining what I said 2 posts up.

Okay this is going to be a crash course in Algebraic functions,
Here we go,
Multiplying fractions is just like multiplying whole numbers. Therefore 1/15 * 1/15 would be eqivilent to 1 * 1 and 15 * 15. So now we have 1 and 225. These are simply the numerator and the denominator of the fraction. So we get 1/225. Now when applying this to possibilities and stratagies. {Starting simple} Imagine a coin toss. The probability of it landing in your favor is 1/2. Heads or Tails. Now imagine layering this same process. If the coin is flipped twice, this means that you have a 1/2 and 1/2 chance of it landing in your favor. So, you have to count off every possible outcome this would be. {h=heads, t=tails} {hh, ht, th, tt} Still following? Okay, now we see there are four possible outcomes, agree? Okay, so now lets try and develop a formula. Looking at the numerator, or top half of the fraction, we see that we have 1 and 1. This only represents one of the possible outcomes, so we turn to the denominator, or bottom half of the fraction. 2 and 2, these represent all of the possible outcomes. In this single case adding them together would get us the correct answer of 4, but this is the only coincidince in which that will happen. So, we will multiply these 2 numbers together. This will give us the correct answer of 4. Now, applying this formula to a password. Let us say yours, we have 5 {flips of the coin} or spaces to fill so we start off with 1/x * 1/x * 1/x * 1/x * 1/x. {x being any number at this point} And in your password problem you said that there were 15 possible character choices so now we complete the equation. 1/15 * 1/15 * 1/15 * 1/15 * 1/15. Now following off step by step we would have 1*1*1*1*1=1 and then 15*15*15*15*15=759375. So, the probability of guessing or picking out the correct password is 1 out of 759375.
• March 24th, 2002, 02:09 PM
ac1dsp3ctrum
The3ntropy, Good post man :) I like your avatar... Are you a tranceaddict?
• March 24th, 2002, 02:38 PM
pakdhe
wow wow wow

i see a calculus class at here
• March 24th, 2002, 03:49 PM
The3ntropy
>>Acid, hell ya, I love trace. That is one of my favorite sites. :)
>>pakdhe, yes I am pretty good at math, got up to Calculus 4 in college. No reason really, just always interested and intrigued by math. {Favorite subject I guess}