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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int T; cin >> T;
    while(T--){
        long long N,M; cin >> N >> M;
        long long low = 0,high = 1e10;
        while(high-low > 1){
            long long mid = (high+low)/2;
            long long one = 4*mid,two = 2*mid;
            two -= M,two = max(two,0LL);
            long long block = N;
            block -= (two+3)/4*2;
            if(block >= one) low = mid;
            else high = mid;
        }
        cout << low*3 << "\n";
    }
}