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

void solve() {
    int n,k;
    cin>>n>>k;
    if(n>k)cout<<0<<endl;
    else{
        ll temp=k-n;
        ll ans=temp;
        ll i=1;
        while(n<=k){
            n+=n;
            i++;
            ans=max(ans,i*(k-n));

        }
        cout<<ans<<endl;
    }

}

int main(){
    int t;
    cin>>t;
    while(t--){
        solve();
    }
return 0;
}