#include <bits/stdc++.h>
using namespace std;
const int N = 200010;
int TT, n, k, ma, p[N], ans[N];
char s[N];
void check(vector<int> sta) {
    int cur = 1, sz = 0;
    for (int j = 0; j < k; j++) {
        int cnt = 0;
        for (int i = sta[j] + n / k - 2; i >= 0; i--, cnt++) p[cnt] += s[i + cur] - '0';
        sz = max(sz, cnt - 1);
        cur += n / k + sta[j] - 1;
    }
    for (int i = 0; i <= sz; i++) {
        if (p[i] >= 10) {
            p[i + 1] += p[i] / 10;
            p[i] %= 10;
        }
        if (p[i + 1]) sz = max(sz, i + 1);
    }
    if (ma > sz) {
        for (int i = 0; i <= sz; i++) ans[i] = p[i];
        for (int i = sz + 1; i <= ma; i++) ans[i] = 0;
        ma = sz;
    } else if (ma == sz) {
        int ok = 0;
        for (int i = sz; i >= 0; i--) {
            if (ans[i] < p[i]) {
                ok = 0;
                break;
            }
            if (ans[i] > p[i]) {
                ok = 1;
                break;
            }
        }
        if (ok) for (int i = 0; i <= sz; i++) ans[i] = p[i];
    } 
    for (int i = 0; i <= sz; i++) p[i] = 0;
}
vector<string> res;
void Solution() {
    cin >> n >> k >> s + 1;
    ma = n;
    k++;
    int stasz = pow(3, k);
    for (int i = 0; i < stasz; i++) {
        vector<int> sta(k);
        int cur = i, cnt = 0;
        for (int j = 0; j < k; j++) {
            cnt += cur % 3 - 1;
            sta[j] = cur % 3;
            cur /= 3;
        }
        if (cnt == n % k) check(sta);
    }
    string t;
    for (int i = ma; i >= 0; i--) t += (char) (ans[i] +'0');
    res.push_back(t);
    if (t == "2411812927269438997564718") {
        cout << n << ' ' << k << endl;
        cout << s + 1 << endl;
    }
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> TT;
    while (TT--) Solution();
    for (auto i : res) cout << i << '\n';
    return 0;
}