#include<bits/stdc++.h>
#define fi first
#define se second
#define MULT_TEST 1
using namespace std;
typedef long double ldb;
typedef unsigned long long ull;
const int INF = 0x3f3f3f3f;
const int MOD = 998244353;
const int N = 200050;
char s[N];
int t[N], ans[N];
inline int read() {
    int w = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        w = (w << 1) + (w << 3) + ch - 48;
        ch = getchar();
    }
    return w * f;
}
inline void Add(int l, int r) {
    int len = r - l + 1;
    for (int i = 0; i <= len; i++) {
        if (r - i >= l) t[i] += s[r - i] - '0';
        t[i + 1] += t[i] / 10;
        t[i] %= 10; 
    }
}
inline void Solve() {
    int n, k;
    n = read(); k = read();
    scanf("%s", s + 1);
    int op = n % (k + 1), len = n / (k + 1);
    for (int i = 0; i <= n; i++) ans[i] = 9;
    for (int S = 0; S < (1 << (k + 1)); S++) {
        if (__builtin_popcount(S) != op) continue;
        int id = 0;
        for (int i = 0; i <= n; i++) t[i] = 0;
        for (int i = 1; i <= k + 1; i++) {
            if ((S >> (i - 1)) & 1) Add(id + 1, id + len + 1), id += len + 1;
            else Add(id + 1, id + len), id += len;
        }
        for (int i = 0; i <= len + 2; i++) 
            if (t[i] >= 10) t[i + 1] += t[i] / 10, t[i] %= 10;
        bool flag = 0;
        for (int i = len + 2; i >= 0; i--) {
            if (t[i] == ans[i]) continue;
            if (t[i] < ans[i]) flag = 1;
            break;
        }
        if (!flag) continue;
        for (int i = 0; i <= n; i++) ans[i] = t[i];
    }
    bool flag = 0;
    for (int i = n; i >= 0; i--) {
        if (ans[i] != 0) flag = 1;
        if (flag) printf("%d", ans[i]);
    }
    if (!flag) printf("0");
    puts("");
}
signed main() {
    int _ = 1;
#if MULT_TEST
    _ = read();
#endif 
    while (_--) Solve();
    return 0;
}
/*
8 1
45455151
*/