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Total number of different combination

  1. May 21, 2014 #1
    I know that if you have 4 numbers eg. 1,23,4 then the total number fo diffferent combination is
    4*3*2*1 = 24
    what about if one number is the same eg. 1966

    Thank you
  2. jcsd
  3. May 21, 2014 #2

    Stephen Tashi

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    Science Advisor

    Are you asking about "permutations" or "combinations"?
  4. May 21, 2014 #3
    so if I had the number 4573 what would be the total permutations?
    and similarly 1966 total permutations
  5. May 21, 2014 #4


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    Staff: Mentor

    24, as you calculated.

    12. Imagine that the two sixes are different (e.g., different colors). You start by counting 4x3x2x1, but that means that you have overcounted because 6169 is the same as 6169. You then simply divide by two to remove the overcounting: 4! / 2 = 12.
  6. May 22, 2014 #5
    colours makes perfect sense
  7. May 25, 2014 #6
    I believe you need to divide by 2 factorial, NOT 2.
    Yes it is the same in this problem
    But not if 3 or more are the same.
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