Question 919004
<pre>
Use 

1.  The identity C(A,B) = C(A,A-B)

and

2. C(A,B) = {{{(matrix(1,4,A*(A-1)*""*""*"", to,B,factors))/B!}}}

C(n,n-2) = C(n,n-(n-2)) = C(n,n-n+2) = C(n,2) = {{{n(n-1)/2!}}} = {{{n(n-1)/2}}}

Edwin</pre>