Combinations/Permutations where only certain elements in series can vary

n00b123

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Feb 19, 2018
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Hi all,

I am sorry if this is posted the wrong sub-forum, but my math knowledge is limited and so I am unsure where else to post.

I am wondering how to calculate the number of possible versions of a series of characters, where only some characters in the series can vary.

5NMB RTTM 8L60 9P7U AJQW 9889

5NMBRTTM8L609P7UAJQW9889
L

N

GO

4

3
V
BB


How many different combinations are possible where only bold characters can vary and they can vary only with the character directly beneath them in the table? Is there a formula for this?

Therefore, the following are possible (characters in red are variations on the original series):

5NMB LTTM 8L60 9P4U AJQW 9889

5NMB RTTM 8L60 9P7U AJQW 9BB9

5NMB LTTN 8LGO 9P4U A3QV 9889

But the following is NOT:

5NMB NTTO 8L60 9P7U ABQB 93V9

I hope this makes sense, and I hope it is ok to post here. I am new to the forum so forgive me if my posting etiquette or anything is off-point.

I look forward to your responses.
 
If I understand the problem, you have a sequence of characters. At specific spots in the sequence, a character may be replaced by one other character.

You have 9 spots where an alternative is permitted.

So the number of possible different sequences is \(\displaystyle 2^9 = 512.\)
 
If I understand the problem, you have a sequence of characters. At specific spots in the sequence, a character may be replaced by one other character.

You have 9 spots where an alternative is permitted.

So the number of possible different sequences is \(\displaystyle 2^9 = 512.\)

Hi, thanks so much for your reply. So if all of those 9 alternatives was available to all 9 spots it would be 9^9?
 
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