#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int tt;
  cin >> tt;
  while (tt--) {
    int n, k;
    cin >> n >> k;
    k += 1;
    string s;
    cin >> s;
    vector<int> g;
    for (int i = 0; i < k; i++) {
      g.push_back(n / k);
    }
    auto Add = [&](string s, string t) {
      reverse(s.begin(), s.end());
      reverse(t.begin(), t.end());
      int carry = 0;
      int ptr = 0;
      string res = "";
      while (ptr < int(s.size()) || ptr < int(t.size()) || carry != 0) {
        int ds = (ptr < int(s.size()) ? int(s[ptr] - '0') : 0);
        int dt = (ptr < int(t.size()) ? int(t[ptr] - '0') : 0);
        int d = (ds + dt + carry) % 10;
        res += char('0' + d);
        carry = (ds + dt + carry) / 10;
        ptr += 1;
      }
      reverse(res.begin(), res.end());
      return res;
    };
    int c = (n / k) * k;
    string res = "";
    for (int mask = 0; mask < (1 << k); mask++) {
      if (c + __builtin_popcount(mask) != n) {
        continue;
      }
      for (int i = 0; i < k; i++) {
        if (mask >> i & 1) {
          g[i] += 1;
        }
      }
      int ptr = 0;
      string sum = "0";
      for (int i = 0; i < k; i++) {
        string cur = "";
        for (int j = 0; j < g[i]; j++) {
          cur += s[ptr];
          ptr += 1;
        }
        sum = Add(sum, cur);
      }
      if (res.empty()) {
        res = sum;
      } else {
        if (int(res.size()) > int(sum.size())) {
          res = sum;
        } else {
          res = min(res, sum);
        }
      }
      for (int i = 0; i < k; i++) {
        if (mask >> i & 1) {
          g[i] -= 1;
        }
      }
    }
    cout << res << '\n';
  }
  return 0; 
}