#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

void solve()
{
  string x;
  int m;
  cin >> x >> m;
  int siz = x.size();
  vector<long long> v(1000, -1);
  for (int i = 0; i < 1000; ++i)
  {
    long long tmp = (long long)i * m;
    if (v[tmp % 1000] == -1) v[tmp % 1000] = tmp;
  } 
  for (int i = siz; i <= 18; ++i)
  {
    string ans(i, '#');
    for (int j = 0; j < siz; ++j)
    {
      ans[j] = x[j];
      ans[i - siz + j] = x[j];
    }
    if (ans.substr(0, siz) != x || ans.substr(i - siz, siz) != x) continue;
    long long d = 0;
    for (auto c : ans) d = (d * 10LL + (c == '#' ? 0 : c - '0')) % m;
    d = (m - d) % m;
    if (d == 0)
    {
      for (auto &c : ans) if (c == '#') c = '0';
      cout << ans << endl;
      return;
    }
    int flag = 1;
    int nok = (((1000 - d) % 1000 + 1000) % 1000);
    if (v[nok] != -1)
    {
      long long tmp = v[nok] + d;
      tmp /= 1000;
      for (int k = i - 4; k >= 0 && tmp > 0; --k)
      {
        ans[k] = tmp % 10 + '0';
        tmp /= 10;
      }
      if (tmp > 0) continue;
      flag = 0;
    }
    for (auto c : ans) if (c == '#') flag = 1;
    if (ans.substr(0, siz) != x || ans.substr(i - siz, siz) != x) flag = 1;
    if (flag) continue;
    cout << ans << endl;
    return;
  }
  cout << -1 << endl;
}

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