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Re: Computing nCr how?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg94838] Re: [mg94820] Computing nCr how?
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Mon, 29 Dec 2008 06:33:26 -0500 (EST)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200812271203.HAA12436@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

An unfortunate, but standard mathematical term -- "combinations".  You 
mean the number of r-element subsets of an n-element set.  This is the 
binomial coefficient often denoted

            n
           ( )
            r

(with a large pair of parentheses).

This is the same, of course, as the coefficient of x^r in the expansion 
of the binomial power (1+x)^n.  In Mathematica, this binomial 
coefficient is:

   Binomial[n,r]


Affan wrote:
> Hi,
> I know this sounds simple but I cant find the function in mathematica
> to compute nCr (i.e. number of combination for n obj chosen in groups
> of r). Can anyone help?
> 
> Thanks
> 
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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