#include<queue>
#include<math.h>
#include<stdio.h>
#include<string.h>
#include<string>
#include<iostream>
#include<algorithm>
using namespace std;
#define N 2005
#define INF 0x3f3f3f3f

long long f[N],n,m;
int Cmn(int m, int n)
{
    if(m < n || n < 0) return 0;
    if(m == n || n == 0) return 1;
    return (Cmn(m-1, n-1) + Cmn(m-1, n));
}

int main()
{
    f[1]=0;f[2]=1;
    for(int i=3;i<25;i++)
        f[i]=(i-1)*(f[i-1]+f[i-2]);
    int T;cin>>T;
    while(T--)
    {
        scanf("%d%d",&n,&m);

        cout<<Cmn(n,m)*f[m]<<endl;
    }

    return 0;
}

/*

*/

//freopen("1.txt", "r", stdin);
    //freopen("2.txt", "w", stdout);