Question 939593
<pre>
{{{(matrix(2,1,n,r))}}}{{{""=""}}}{{{n!/(r!(n-r)!)}}}

Replace r by (n-r)   

{{{(matrix(2,1,n,(n-r)))}}}{{{""=""}}}{{{n!/((n-r)!^""(n^""-(n-r))!)}}}

{{{(matrix(2,1,n,n-r))}}}{{{""=""}}}{{{n!/((n-r)!(n-n+r)!)}}}

{{{(matrix(2,1,n,n-r))}}}{{{""=""}}}{{{n!/((n-r)!r!)}}}{{{""=""}}}{{{n!/(r!(n-r)!)}}}{{{""=""}}}{{{(matrix(2,1,n,r))}}}

Edwin</pre>