#ifdef MY_LOCAL
#include "D://competitive_programming/debug/debug.h"
#define debug(x) cerr << "[" << #x<< "]:"<<x<<"\n"
#else
#define debug(x) 
#endif
#define REP(i, n) for(int i = 0; i < (n); i ++)
#define REPL(i,m, n) for(int i = (m); i < (n); i ++)
#define SORT(arr) sort(arr.begin(), arr.end())
#define LSOne(S) ((S)&-(S))
#define sz(X) ((int)X.size())
#define READ(arr) for(auto &a: arr){cin>>a;}
#define SUM(arr) accumulate((arr).begin(), (arr).end(), 0LL)
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long ll;
#define int ll
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<vii> vvii;
typedef tree<int,null_type,less<int>, rb_tree_tag, tree_order_statistics_node_update> ost;
const ll INF = 1e18;
string add_s(string s1, string s2) {
	string vv;
	int ptr1 = sz(s1)-1;
	int ptr2 = sz(s2)-1;
	int carry = 0;
	//debug(s1);debug(s2);
	while (ptr1 >= 0 || ptr2 >= 0) {
		int v1 = (ptr1 < 0 ? 0 : s1[ptr1] - '0');
		int v2 = (ptr2 < 0 ? 0 : s2[ptr2] - '0');
		//debug(v1);debug(v2);
		int tot = v1 + v2 + carry;
		if (tot >= 10) {
			tot -= 10;
			carry = 1;
		} else {
			carry = 0;
		}
		vv += (char)('0' + tot);
		ptr1--;
		ptr2--;
	}
	if (carry == 1) {
		vv += '1';
	}
	reverse(vv.begin(), vv.end());
	return vv;
}

string get_smaller(string s1, string s2) {
	if (sz(s1) < sz(s2)) {
		return s1;
	} else if (sz(s2) < sz(s1)) {
		return s2;
	} else {
		if (s1 < s2) {
			return s1;
		} else {
			return s2;
		}
	}
}
string solve() {
	int n,k;cin>>n>>k;k++;
	string s;cin>>s;
	int baseline = n/k;
	int excess = n%k;
	vector<vector<string>> dp(k+1, vector<string>(excess+1, "."));
	dp[1][0] = s.substr(0, baseline);
	if (excess != 0) {
		dp[1][1] = s.substr(0, baseline + 1);
	}
	//debug(dp);
	REPL(which, 2, k+1) {
		REP(curex, min(excess,  which) + 1) {
			// have excess...
			string s1 = ".";
			string s2 = ".";
			if (curex != 0) {
				// use excess here....
				int starting = (which - 1)*baseline + (curex-1);
				s1 = add_s(s.substr(starting, baseline + 1), dp[which-1][curex-1]);
			}
			if (curex != which) {
				int starting = (which - 1)*baseline + curex;
				//debug(starting);
				string tt = s.substr(starting, baseline);
				//debug(tt);
				//debug(dp[which-1][curex]);
				s2 = add_s(tt, dp[which-1][curex]);
			}
			//debug(s1);debug(s2);
			if (s1 == ".") {
				dp[which][curex] = s2;
			} else if (s2 == ".") {
				dp[which][curex] = s1; 
			} else {
				dp[which][curex] = get_smaller(s2, s1);
			}
		}
	}
	//debug(dp);
	return dp[k][excess];
}
signed main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int tc;cin>>tc;
	REP(i, tc) {
		cout<<solve()<<"\n";
	}
}