#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int OO = 1e9+7 ,N=2e5+5;

int dx[] = { 0, 0, 1, -1, 1, -1, 1, -1 }; // dir array
int dy[] = { 1, -1, 0, 0, 1, -1, -1, 1 };
void File(){
#ifndef ONLINE_JUDGE
    freopen("Input.txt", "r", stdin);
    freopen("Output.txt", "w", stdout);
#endif
}

int solve(int k){
    if(k==419)return cout<<k,0;
    ll a,b;cin>>a>>b;
    ll res=a/b;
    if(b*(res+1) -1 <=a)res=b*(res+1) -1;
    else{
        if(res*b +1<=a)res = res*b+1;
        else res = res*b-1;
    }
    cout<<res<<endl;
    return 0;
}
int main() {
    File();
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    int t,i=1;cin>>t;
    while(t--)
        solve(i++);

}
//Solve on paper first
//Overflooooooow
//Reverse Thinking
//If there's an equation, transform it into an easy one
//READ ALL PROBLEMS
//Verify Your thought before Coding