#include <bits/stdc++.h>
#define DEBUG 0
#define CASES 1
using namespace std;
const int SZ = 2e5 + 7;
const int MX = 1e9 + 7;
const long long MOD = 1e9 + 7;
const long long MXX = (1LL << 61LL);

string s;
int x, y;

string plusz(string a, string b) {
    int as = a.size(), bs = b.size();
    if(a.size() < b.size()) {
        reverse(a.begin(), a.end());
        for(int i=0; i<bs-as; i++) a += '0';
        reverse(a.begin(), a.end());
    }
    else {
        reverse(b.begin(), b.end());
        for(int i=0; i<as-bs; i++) b += '0';
        reverse(b.begin(), b.end());
    }

    string res = "";
    int tod = 0;

    for(int i=a.size()-1; i>-1; i--) {
        int val = a[i] + b[i] - 2*'0' + tod;
        res += char((val%10) + '0');
        tod = val/10;
    }

    if(tod) res += '1';
    reverse(res.begin(), res.end());

    return res;
}

string smin(string a, string b) {
    if(a.size() < b.size() || b == "") return a;
    else if(a.size() > b.size() || a == "") return b;

    for(int i=0; i<a.size(); i++) {
        if(a[i] < b[i]) return a;
        else if(a[i] > b[i]) return b;
    }

    return a;
}

string recur(int p, int l, int r) {
    if(l == 0 && r == 0) return "0";
    string g = "", v = "", A = "", B = "";
    for(int i=p; i>p-x; i--) g += s[i];
    reverse(g.begin(), g.end());
    v = s[p-x] + g;

    if(l > 0) A = plusz(g, recur(p-x, l-1, r));
    if(r > 0) B = plusz(v, recur(p-x-1, l, r-1));

    return smin(A, B);
}

void process(void) {
    int n, k;
    cin >> n >> k >> s;
    x = n/(k+1), y = n%(k+1);

    cout << recur(n-1, k+1-y, y) << '\n';
    return ;
}

int main() {
    #ifndef DEBUG
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    #endif
    cin.tie(nullptr)->ios::sync_with_stdio(false);
    int t(1);
    if(CASES) cin >> t;
    while(t--) process();
}