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

#define rep(i,n) for(ll i=0;i<n;++i)
#define all(a) (a).begin(),(a).end()
ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; }
ll modpow(ll a, ll b, ll p){ ll ans = 1; while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; }
template<class T> T div_floor(T a, T b) { return a / b - ((a ^ b) < 0 && a % b); }
template<class T> T div_ceil(T a, T b) { return a / b + ((a ^ b) > 0 && a % b); }
template <typename T, typename U> inline bool chmin(T &x, U y) { return (y < x) ? (x = y, true) : false; }
template <typename T, typename U> inline bool chmax(T &x, U y) { return (x < y) ? (x = y, true) : false; }

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &a){
    if (a.empty()) return os;
    os << a.front();
    for (auto e : a | views::drop(1)){
        os << ' ' << e;
    }
    return os;
}

void dump(auto ...vs){
    ((cout << vs << ' '), ...) << endl;
}

#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;

ll solve_all(ll X,ll M,ll e){
    ll ans=2e18;
    ll te=intpow(10,e);
    for (ll d=e;d<=18-e;d++){
        ll r=X*(1+pow_mod(10,d,M));
        r=M-r;
        r%=M;
        r+=M;
        r%=M;
        ll g=gcd(te,M);
        ll tg=te/g;
        ll mg=M/g;
        if (r%g!=0){
            continue;
        }
        r/=g;
        ll y=r*inv_mod(tg,mg);
        y%=mg;
        if (y<intpow(10,d-e)){
            chmin(ans,X*(1+intpow(10,d))+y*te);
        }
    }
    return ans;
}

void solve1(ll X,ll M){
    string xs=to_string(X);
    if (X%M==0){
        cout<<X<<'\n';
        return;
    }
    ll ans=solve_all(X,M,1);
    if (ans>=1e18){
        cout<<-1<<'\n';
    }
    else{
        cout<<ans<<'\n';
    }
    return;
}

void solve2(ll X,ll M){
    string xs=to_string(X);
    if (X%M==0){
        cout<<X<<'\n';
        return;
    }
    if (xs[0]==xs[1]){
        ll a=(xs[0]-'0')*100+X;
        if (a%M==0){
            cout<<a<<'\n';
            return;
        }
    }
    ll ans=solve_all(X,M,2);
    if (ans>=1e18){
        cout<<-1<<'\n';
    }
    else{
        cout<<ans<<'\n';
    }
}

void solve3(ll X,ll M){
    string xs=to_string(X);
    if (X%M==0){
        cout<<X<<'\n';
        return;
    }
    if (xs[0]==xs[1] and xs[1]==xs[2]){
        ll a=(xs[0]-'0')*1000+X;
        if (a%M==0){
            cout<<a<<'\n';
            return;
        }
    }
    if (xs[0]==xs[2]){
        ll a=(xs[0]-'0')*10000+(xs[1]-'0')*1000+X;
        if (a%M==0){
            cout<<a<<'\n';
            return;
        }
    }
    ll ans=solve_all(X,M,3);
    if (ans>=1e18){
        cout<<-1<<'\n';
    }
    else{
        cout<<ans<<'\n';
    }
}

void solve() {
    ll X,M;
    cin>>X>>M;
    string xs=to_string(X);
    if (xs.size()==1){
        solve1(X,M);
    }
    else if (xs.size()==2){
        solve2(X,M);
    }
    else if (xs.size()==3){
        solve3(X,M);
    }
    return;
}


int main() {
    cin.tie(0)->sync_with_stdio(0);
    ll T=1;
    cin>>T;
    while (T--){
        solve();
    }
    return 0;
}