iiitv/ChefLib

/*
    Made by:
        ``` Monal Shadi ``
    Github: Monal5031
    Codechef: monalshadi
*/

#include "bits/stdc++.h"

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int tc;
    cin >> tc;
    while (tc--) {
        long long n, b;
        cin >> n >> b;
        if (n <= b) {
            cout << "0\n";
            continue;
        }
        else if (b > n / 2) {
            cout << n % b << "\n";
            continue;
        }
        unsigned long long a = n / b;
        unsigned long long t = a;
        a = ceil(a / 2.0);
        cout << (n - a*b) * (a) << "\n";
    }
    return 0;
}