#include <iostream>
#include <iomanip>
 
using namespace std;
 
void newton( int n, int k );
long double fact( int f );
 
int main()
{
   int t;
 
   cin >> t;
 
   for ( int i = 1; i <= t; i++ )
   {
       int n, k;
       cin >> n >> k;
 
       if ( k > n/2 )
            k = n - k;
 
       newton(n,k);
   }
}
 
long double fact( int f )
{
    if ( f == 0 ) return 1;
    else return f * fact(f-1);
}
 
void newton( int x, int y )
{
    long double fact1, fact2, fact3;
 
    fact1 = fact(x);
    fact2 = fact(y);
    fact3 = fact(x-y);
 
    cout << setprecision(1000);
    cout << fact1 / (fact2 * fact3) << endl;
}
 
 

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MTAwMCAxMDA=

1000 100