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Please help-I'm really mixed up

How do I find the permutations of the first 12 letters taken 3 at a time?

I have a ton of these to do and really don't understand them at all-

Question ID
525386

Created
April 4, 2011 9:29pm UTC

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0

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https://questions.llc/questions/525386

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2

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466

2 answers

  1. permutations:

    That means all the arrangements of three made from the 12 when order is important. For example
    ABC and ACB and BAC and BCA and CAB and CBA are all different.
    The formula for that is
    n!/[n-r]!
    here n = 12 and r = 3
    so we have
    12!/9! which is 12*11*10 = 132
    That is what you asked.

    To answer what is coming next, combinations of n taken r at a time where order is NOT important are called indeed combinations and the formula is logically enough the permutation formula divided by r!
    C(n,r) = n!/[ r! (n-r)! ]

    Answer ID
    525392

    Created
    April 4, 2011 9:38pm UTC

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    0

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  2. Thank you for the explanation-it actually makes sense now

    Answer ID
    525396

    Created
    April 4, 2011 9:54pm UTC

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    0

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