A transaction ID generator generates random, 27 character strings from the set of lower case and upper case letters and single digits without repetition (a-z,

Without any character repeating

okay we have [ABC] and   59 other characters to choose from to make a string of 27   (24+3)

(25*59P24) / 62P27

25*nPr(59,24)/nPr(62,27) = 0.0001101709853693

approx 1  in 10,000

I think that is correct.       

and the 28 in my last answser that was wrong anyway shoud have be 25 - silly me.

My reasoning is as follows:

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Hello Alan: Can the font of your software package be made a little larger?

Even with eye glasses, my eyes have a rough time reading your answers! Thanks.

Hi Alan, 

I am not saying your answer is wrong - I am just not necessarily convinced it is right.

Here is another possibility (probably wrong)

Say we stick an ABC together so that instead of choosing 27 characters we choose 24 plus our one lot of joined letters.

Then the answer could  be

\(\frac{28*62^{24}}{62^{27}}=\frac{28}{62^{3}}=\frac{28}{238328}\)

28/238328 = 0.0001174851465208

So that is about 1 in 10,000

Much more often than what Alan got.

I do not think that this is correct because The ABC could occur in our not prejoined together sequences.  So I tend to think it would happen more often than this - not less.  :///

idk probability is so confusing  LOL