#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define nl "\n"
#define ws " "
#define FASTIO ios_base::sync_with_stdio(false); cin.tie(NULL);
#define MOD 1000000007

typedef vector<int> vi;
typedef vector<pair<ll, ll>> vii;

int main () {
    FASTIO
    int t;
    cin>>t;
    while (t--) {
        ll n, k;
        cin>>n>>k;
        ll ans = 0, cnt = 1;
        for (ll i = n; i <= (k + 1) / 2; i += n) {
            ans = max (ans, (k - i) * cnt);
            cnt++;
        }
        cout<<ans<<nl;
    }
    return 0;
}