#include<bits/stdc++.h>

using namespace std;

using ll=long long;
const int N=1000050;
//从低向高dp
string n,m;
int Nlen,Mlen;
int dp[N][12][2][2];
int ans[N];
int nxt[20];
int Dfs(int i,int j,int mark,int up)
{
    if(i==0) return mark;
    if(dp[i][j][mark][up]!=-1) return dp[i][j][mark][up];
    int low=0;
    if(up) low=n[i]-'0';
    for(int now=low;now<=9;now++)
    {
        int nxtj=j;
        while(nxtj && m[nxtj+1]!=now+'0') nxtj=nxt[nxtj];
        if(m[nxtj+1]==now+'0') nxtj++;
        int nxtmark=mark;
        if(nxtj==Mlen)
        {
            // cerr<<"Mark: "<<i<<" "<<j<<" "<<now<<"|"<<Mlen<<"\n";
            nxtj=nxt[nxtj];
            nxtmark=1;
        }
        // if(i==3) cerr<<"Dfs:"<<i<<" "<<j<<" "<<mark<<" "<<up<<"="<<now<<"---"<<nxtmark<<" "<<nxtj<<"\n";
        if(Dfs(i-1,nxtj,nxtmark,up && now==low))
        {
            ans[i]=now;
            
            return dp[i][j][mark][up]=1;
        }
    }
    return dp[i][j][mark][up]=0;
}
string Remove(string s)
{
    int p=0;
    while(p+1<s.size() && s[p]=='0') p++;
    return s.substr(p,s.size()-p);
}
string Solve2(string a,string b)
{
    int num=0;
    for(int i=0;i<(int)b.length();i++)
        num*=10,num+=b[i]-'0';
    int p=0;
    ll cur=0;
    while(p<a.size())
    {
        cur*=10;
        cur+=a[p]-'0';
        cur%=num;
        p++;
    }
    // cout<<cur<<"%\n";
    int need=num-cur;
    reverse(a.begin(),a.end());
    string add;
    while(need) add+=need%10+'0',need/=10;
    a+="000000000000000000000000000000000";
    for(int i=0;i<a.size();i++)
    {
        if(i<add.size()) a[i]+=add[i]-'0';
        int carry=(a[i]-'0')/10;
        a[i]=(a[i]-'0')%10+'0';
        if(i+1<a.size()) a[i+1]+=carry;
    }
    reverse(a.begin(),a.end());

    return Remove(a);
}
void Solve()
{
    cin>>n>>m;
    string Ans2=Solve2(n,m);
    Nlen=n.length(),Mlen=m.length();
    for(int i=0;i<=Nlen+15;i++)
        for(int j=0;j<=11;j++)
            for(int k=0;k<=1;k++)
                for(int l=0;l<=1;l++)
                    dp[i][j][k][l]=-1;
    reverse(n.begin(),n.end());
    n=" "+n;m=" "+m;
    n[1]++;
    int tmp=1;
    while(n[tmp]-'0'>=10)//n++
    {
        n[tmp]='0';
        tmp++;
        n[tmp]++;
    }
    n=n+"000000000000000000000";
    // cout<<"n="<<n<<",m="<<m<<"\n";
    for(int i=2,j=0;i<=Mlen;i++)
    {
        while(j && m[i]!=m[j+1]) j=nxt[j];
        if(m[i]==m[j+1]) j++;
        nxt[i]=j;
    }
    // for(int i=1;i<=Mlen;i++)
    //     cerr<<nxt[i]<<" ";
    // cerr<<endl;
    Dfs(Nlen+12,0,0,1);
    string ans1;
    for(int i=Nlen+12;i>=1;i--)
        ans1+=ans[i]+'0';
    string Ans1=Remove(ans1);
    // cout<<Ans1<<" "<<Ans2<<" ";
    if(Ans1.size()<Ans2.size())
    {
        cout<<Ans1<<"\n";
    }
    else if(Ans1.size()==Ans2.size() && Ans1<Ans2)
    {
        cout<<Ans1<<"\n";
    }
    else
    {
        cout<<Ans2<<"\n";
    }
    
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int t=1;
    cin>>t;
    while(t--) Solve();
    return 0;
}