#include <bits/stdc++.h>

#define eb emplace_back
#define ep emplace
#define fi first
#define se second
#define in read<int>()
#define lin read<ll>()
#define rep(i, x, y) for(int i = (x); i <= (y); i++)
#define per(i, x, y) for(int i = (x); i >= (y); i--)

using namespace std;

using ll = long long;
using db = double;
using pii = pair < int, int >;
using vec = vector < int >;
using veg = vector < pii >;

template < typename T > T read() {
	T x = 0; bool f = 0; char ch = getchar();
	while(!isdigit(ch)) f |= ch == '-', ch = getchar();
	while(isdigit(ch)) x = x * 10 + (ch ^ 48), ch = getchar();
	return f ? -x : x;
}

template < typename T > void chkmax(T &x, const T &y) { x = x > y ? x : y; }
template < typename T > void chkmin(T &x, const T &y) { x = x < y ? x : y; }

const int N = 1e6 + 10;
//constexpr ll B = 1e16;
constexpr int B = 10;

int n, K;
string num;

vec tnum;
const bool operator < (const vec &x, const vec &y) {
	//cerr << "!COMP: " << x << " " << y << endl;
	if(x.size() != y.size()) return x.size() < y.size();
	per(i, (int)x.size() - 1, 0)
		if(x[i] != y[i]) return x[i] < y[i];
	return 1;
}

ll pw[20];

int len;

vec get(vec pot) {
	int cur = 1; vec ret(len + 4, 0);
	for(auto v : pot) {
		int l = cur, r = l + v - 1;
		//cerr << l << " " << r << " " << getp(l, r) << endl;
		rep(j, l, r)
			ret[r - j] += tnum[j - 1];
		cur += v;
	} 
	rep(j, 0, ret.size() - 1) if(ret[j] >= 10) ret[j + 1] += ret[j] / 10, ret[j] %= 10;
	while(ret.size() && ret.back() == 0) ret.pop_back();
	return ret;
}

void solve() {
	cin >> n >> K >> num;
	vec().swap(tnum); len = n / (K + 1);
	for(auto &v : num) v -= '0', tnum.eb(v);
	vec ans; bool fl = 0;
	auto upd = [&](vec ret) {
		if(!fl) ans = ret, fl = 1;
		else chkmin(ans, ret);
	};
	function < void(int, int, int, vec) > dfs = [&](int tot, int mn, int mx, vec pot) {
		if(mx - mn > 2) return;
		if(tot >= n) return;
		if(pot.size() == K) {
			chkmin(mn, n - tot), chkmax(mx, n - tot);
			if(mx - mn > 2) return; pot.eb(n - tot); upd(get(pot)); return;
		}
		rep(i, max(1, len - 1), len + 2) {
			pot.eb(i);
			dfs(tot + i, min(mn, i), max(mx, i), pot);
			pot.pop_back();
		}
	};
	dfs(0, n, 0, { });
	reverse(ans.begin(), ans.end());
	for(auto v : ans) cout << v; cout << endl;
}

int main() {
#ifdef YJR_2333_TEST
	freopen("1.in", "r", stdin);
#endif
	pw[0] = 1; rep(i, 1, 18) pw[i] = pw[i - 1] * 10;
	ios :: sync_with_stdio(false), cin.tie(0), cout.tie(0);
	int T; cin >> T;
	for(; T; T--) solve(); return 0;
}