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I'm in quite the weird position where I have to get "pairs" from three digit numbers

For example, the number $123$ gets the "pairs" : $12$ $13$ $21$ $23$ $31$ $32$ - what is this called?

Jacob
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  • Perhaps "subset"? –  Jul 25 '13 at 20:55
  • @DannyCheuk Notice that they are ordered. Thus calling them transpositions in ${1,2,3}$ would not work either. – Karl Kroningfeld Jul 25 '13 at 20:56
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    I think it's a 2 permutation of 3 elements. See here for more details: http://de.wikipedia.org/wiki/Permutation – sigmatau Jul 25 '13 at 20:57
  • @Jacob more context would be helpful. Why are you interested in what these are called? Do you also want to know anything about them, like how many there are? – Caleb Stanford Jul 25 '13 at 21:03
  • Well I do think that Amire Bendjeddou is right with what it is called - but I have to do the "pairing" or permutations with 12,269 numbers and was really looking for the name due to know if there is any software that can assist me. – Jacob Jul 25 '13 at 21:07
  • Ordered pairs, I would suggest, rather than subsets or permutations (we have both $12$ and $21$) - but I would agree with @Goos that it would greatly help to know the context. And it would be useful to know what the pairs would be from $122$ before answering. – Mark Bennet Jul 25 '13 at 21:07
  • My initial question was just to know what it was called - but what I would do with numbers is as follows: I get the number 122 and get the numbers 12, 12, 22 and just those numbers alone because the pairings do not count in reverse - and they have to be one of 55 numbers - 01 02 03 04 05 06 07 08 09 11 12 13 14 15 16 17 18 19 22 23 24 25 26 27 28 29 33 34 35 36 37 38 39 44 45 46 47 48 49 55 56 57 58 59 66 67 68 69 77 78 79 88 89 99 - the numbers can reverse positions to fit in any of these numbers. I'm sorry if this is nonsense but I am getting paid to do this. – Jacob Jul 25 '13 at 21:11
  • @Jacob, I think you mean one of 54 numbers, not 55, unless you meant to also allow 00 as a possible pairing. – Barry Cipra Jul 25 '13 at 21:34
  • Again - thank you guys for your time. I truly appreciate it even if this is something extremely simple to you. @Barry Cipra I do! nice catch. – Jacob Jul 25 '13 at 21:35

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