#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,s,n) for (int i = (s); i < (n); ++i)
#define rrep(i,n,g) for (int i = (n)-1; i >= (g); --i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define len(x) (int)(x).size()
#define dup(x,y) (((x)+(y)-1)/(y))
#define pb push_back
#define eb emplace_back
#define Field(T) vector<vector<T>>
using namespace std;
using ll = long long;
using ull = unsigned long long;
template<typename T> using pq = priority_queue<T,vector<T>,greater<T>>;
using P = pair<int,int>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}

// (1/a) % m (aの逆元) を求める;
// m は素数でなくてもよい。
ll modinv(ll a, ll m) {
  ll b = m, u = 1, v = 0;
  while (b) {
    ll t = a / b;
    a -= t * b; swap(a, b);
    u -= t * v; swap(u, v);
  }
  u %= m;
  if (u < 0) u += m;
  return u;
}

void solve() {
  string x; int m;
  cin >> x >> m;
  int k = len(x);
  int tk = 1;
  rep(i,0,k) tk *= 10;
  int g = __gcd(tk, m);
  ll inv = modinv(tk/g, m/g);
  // cout << g << " " << inv << endl;
  rep(n,len(x),19) {
    string s(n, '.');
    rep(i,0,k) s[i] = x[i];
    int ng = 0;
    rep(i,0,k) {
      if (s[i+n-k] != '.' && s[i+n-k] != x[i]) {
        ng = 1;
        break;
      }
      s[i+n-k] = x[i];
    }
    if (ng) continue;
    // cout << s << endl;
    if (n <= 2*k) {
      if (stoi(s)%m == 0) {
        cout << s << endl;
        return;
      }
      continue;
    }
    ll v = 0;
    rep(i,0,n) {
      v = (v*10)%m;
      if (s[i] == '.') continue;
      v = (v+(s[i]-'0'))%m;
    }
    v = (m-v)%m;
    // cout << v << " -> " << ((v/g)*inv)%(m/g) << endl;
    if (v%g != 0) continue;
    v = ((v/g)*inv)%(m/g);
    string u = to_string(v);
    if (len(u) <= n-2*k) {
      rep(i,0,len(u)) {
        s[i+n-k-len(u)] = u[i];
      }
      rep(i,0,n) {
        if (s[i] == '.') s[i] = '0';
      }
      cout << s << endl;
      return;
    }
  }
  cout << -1 << endl;
}

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