#include
    
     long long int a[21];long long int fun(int n,int m){    int i;    long long int sum = 1;    m = m>(n-m)?n-m:m;    for(i = 1; i <= m; i ++)        sum = (sum*(n-m+i))/i;    return sum;}int main(){    int i,T,n,m;    a[2] = 1;    a[3] = 2;    for(i = 4;i <= 20;i++)        a[i] = (i-1)*(a[i-1]+a[i-2]);    scanf("%d",&T);    while(T--)    {        scanf("%d%d",&n,&m);        printf("%I64d\n",a[m]*fun(n,n-m));    }    return 0;}