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# count string convinations

Posted on 2013-05-10
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hello there,
I am trying to calculate how many combinations can be made with 25 chars
using "abcdefghijklmnopqrstuvwxy0123456789"

each password is 25 characters total:
77kcu85wqc2elui7cqz7do3ss
52hwgawx6pc7h82h41eosalaj
ymzy5jiv92w03eto4wwu19juk
etc..

how many millions or billions unique combinations can be made?
0
Question by:XK8ER
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LVL 75

Expert Comment

ID: 39156817
This is a permutation problem, where repetition is allowed, it seems. You should find what you need here:

http://www.regentsprep.org/Regents/math/ALGEBRA/APR2/LpermRep.htm
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LVL 43

Expert Comment

ID: 39156846
abcdefghijklmnopqrstuvwxy0123456789

has 35 chars and you need 25 of them

So it would be

35^25
0

LVL 1

Author Comment

ID: 39156889
haa sorry my math skills are a bit low, so exactly do I know the numbers?
0

LVL 43

Expert Comment

ID: 39156922
35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35*35

(25 times)
0

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Author Comment

ID: 39156937
right, but that still doesnt tell me how many trillion or billion?
0

LVL 43

Accepted Solution

Saqib Husain, Syed earned 500 total points
ID: 39156938
3.9966959347247031355112791061401e+38

or

399,669,593,472,470,313,551,127,910,614,010,000,000

The last 7 digits have been rounded to zeros
0

LVL 84

Expert Comment

ID: 39157177
35^25 = 399669593472470313551127910614013671875
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