/* SRIJON
        SINGHA
            SAMANTA */
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
#define nl "\n"
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define yes cout << "YES" << nl
#define no cout << "NO" << nl
#define fi first
#define sec second
#define pb push_back
#define ppb pop_back
#define pf push_front
#define ppf pop_front
#define FIO                           \
    ios_base::sync_with_stdio(false); \
    cin.tie(NULL);                    \
    cout.tie(NULL);
const int mod = 1e9 + 7;
bool good(ll mid, ll b,ll n)
{
    return (mid*n)>=b;
}

int32_t main()
{
    FIO

    ll t;	cin >> t;
    ll tt=t;
    while (tt--)
    {
        ll n,k; cin>>n>>k;
        if(n>=k) cout<<"0"<<nl;
        else
        {
            ll a=k/n,b=k/2;
            ll l=0,r=a;
            while(l+1<r)
            {
                ll mid=(l+r)/2;
                if(good(mid,b,n)) r=mid;
                else l=mid;
            }
            cout<<r*(k-(r*n))<<nl;
        }      
    }
    return 0;
}