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Math question
Posted: Sun Apr 24, 2011 4:07 pm
by MachineCode
If I generate a 20-character password made up of only the letters A through Z, how many combinations of passwords will there be? Is it (20*26)^20, or what? These things always confuse me!

Re: Math question
Posted: Sun Apr 24, 2011 4:25 pm
by Demivec
26 ^ 20
Re: Math question
Posted: Sun Apr 24, 2011 4:47 pm
by skywalk
Also depends if you allow repeats or case sensitive(replace 26 with 52).
2 non-repeating char = 26 * 25 = 650
3 non-repeating char = 26 * 25 * 24 = 15600
repeating char = (nchars) ^ password length = 26 ^ 20 ~= 2e28 passwords.
Re: Math question
Posted: Sun Apr 24, 2011 5:04 pm
by Rook Zimbabwe
2+2 = 5
(for higher values of 2)
26*26*20=13,250
13,250*26*26*20=180,000,000+
non case sensitive only CAPS so... adding lower case and numbers 0-9 you can have every word in the dictionary... spelled and mispelled andmiscapped and nums for L3tt3r5 etc... you have more possible combos than I want to try to conceptualize...

Re: Math question
Posted: Sun Apr 24, 2011 5:05 pm
by MachineCode
Any of the A-Z letters can repeat, and they're all lower-case. So, it looks like it's what Demivec said: 26^20 = 19,928,148,895,209,409,152,340,197,376 combinations? How is that number even expressed in words to a layman?
[Edit] I'll just use the term "gazillions" (
http://www.thefreedictionary.com/gazillions).

Re: Math question
Posted: Sun Apr 24, 2011 5:23 pm
by Rook Zimbabwe
once you exceed 1,009,614 you have exceeded the number of words in the english language... if you add maybe 1,490,000 to that you have all possible mispellings and adding 1,000,000 to that adds in all possible letterreplacedbynumber variations at best!!!

Re: Math question
Posted: Sun Apr 24, 2011 7:29 pm
by Barney
I reckon these guys probably know best:
http://www.oxforddictionaries.com/page/93
Barney