#pragma GCC optimize("O3,unroll-loops")
#include <algorithm>
#include <cmath>
#include <cassert>
#include <iostream>
#include <string>
#include <map>
#include <set>
#include <bitset>
#include <vector>
#include <queue>
#include <numeric>
#include <cstring>
#define f(x, a, b) for (int x = a; x < b; x++)
#define fm(x, a, b) for (int x = a; x > b; x--)
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define mp make_pair
#define sz(a) int((a).size())
using namespace std;
typedef unsigned long long ll;
typedef long long int li;
const li mod=1e9+7;
const int val = 100;
struct bignum {
    int dig[val];
    bignum() {
        memset(dig,0,sizeof(dig));
    }
    bignum(string &s, int l, int r) {
        memset(dig,0,sizeof(dig));
        int j=0;
        fm(i,r-1,l-1) {
            dig[j]=s[i]-'0';
            j++;
        }
    }
    void add(bignum &b) {
        int carry=0;
        f(i,0,val) {
            dig[i]+=b.dig[i]+carry;
            carry=dig[i]/10;
            dig[i]%=10;
        }
    }
    bool greater(bignum &b) {
        fm(i,val-1,-1) {
            if (dig[i]>b.dig[i])
                return true;
            if (dig[i]<b.dig[i])
                return false;
        }
        return false;
    }
    void print() {
        int i=val-1;
        while (i>=0 && dig[i]==0)
            i--;
        if (i==-1)
            cout <<0;
        else {
            fm(j,i,-1)
                cout <<dig[j];
        }
        cout <<"\n";
    }
};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t;
    cin >>t;
    while(t--) {
        int n,k;
        cin >>n>>k;
        k++;
        string s;
        cin >>s;
        int d1 = n/k;
        int ex = n%k;
        string x;
        f(i,0,n)
            x+='9';
        bignum cmax(x,0,n);
        
        f(i,0,1<<k) {
            if (__builtin_popcount(i)==ex) {
                int i1 = 0;
                bignum csum;
                f(j,0,k) {
                    if (i&(1<<j)) {
                        bignum c(s,i1,i1+d1+1);
                        csum.add(c);
                        i1+=d1+1;
                    }
                    else {
                        bignum c(s,i1,i1+d1);
                        csum.add(c);
                        i1+=d1;
                    }
                }
                if (!csum.greater(cmax))
                    swap(csum,cmax);
            }
        }
        cmax.print();
    }
}