#include <bits/stdc++.h>
using namespace std;
bool cmp(int a,int b){
    return a>b;
}
int main() {
    int test;
    double n,m,k;
    scanf("%d",&test);
    while(test--){
        scanf("%lf %lf",&n,&m);
        if(n<=1||m==0){
            printf("0\n");
        }
        else{
            k=0;
             if(n>=2*m){
                 k=2*m*n-m*2*m-m;
            }
            else{
                m=n/2;
                k=2*m*n-m*2*m-m;
            }
            printf("%.0f\n",k);
        }
    }
    return 0;
}