#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
#define rep(i, a, b) for(int i = (a); i <= (b); i ++)
#define per(i, a, b) for(int i = (a); i >= (b); i --)
#define Ede(i, u) for(int i = head[u]; i; i = e[i].nxt)
using namespace std;

#define eb emplace_back

bool Mb;

inline int read() {
	int x = 0, f = 1; char c = getchar();
	while(c < '0' || c > '9') f = (c == '-') ? - 1 : 1, c = getchar();
	while(c >= '0' && c <= '9') x = x * 10 + c - 48, c = getchar();
	return x * f;
}

const int N = 2e5 + 10, inf = 1e9;
const ll base = 1e16;
int n, k, a[N];

struct node {
	ll a[N / 16 + 5]; int len;
	node() {len = inf;}
	
	bool operator < (const node &b) const {
		if(len ^ b.len) return len < b.len;
		per(i, len, 1) if(a[i] ^ b.a[i]) return a[i] < b.a[i];
		return true;
	}
	
	node operator + (const node &b) const {
		node c;
		c.len = max(len, b.len);
		ll cur = 0;
		rep(i, 1, c.len) {
			if(i <= len) cur += a[i];
			if(i <= b.len) cur += b.a[i];
			c.a[i] = cur % base, cur /= base;
		}
		while(cur) c.a[++ c.len] = cur % base, cur /= base;
		return c;
	}
	
	void print() {
		vector<int> ans;
		rep(i, 1, len) {
			ll c = a[i];
			rep(j, 1, 16) ans.eb(c % 10), c /= 10;
		}
		while(!ans.empty() && ans.back() == 0) ans.pop_back();
		reverse(ans.begin(), ans.end());
		if(ans.empty()) putchar('0'); else for(auto o : ans) putchar('0' + o);
		putchar('\n');
	}
	
} f[8][8][8][8];

void cmin(node &x, const node &y) {x = x < y ? x : y;}

node calc(int l, int r) {
	node c; c.len = 0;
	for(int i = r; i >= l; i -= 16) {
		ll cur = 0;
		rep(j, max(l, i - 15), i) cur = cur * 10 + a[j];
		c.a[++ c.len] = cur;
	}
	return c;
}

void solve() {
	n = read(), k = read();
	
	int len1 = n / (k + 1);
	int len0 = (len1 == 1) ? 1 : len1 - 1;
	int len2 = len1 + 1;
	int len3 = len2 + 1;
	
	rep(i, 1, n) {
		char c = getchar();
		while(c < '0' || c > '9') c = getchar();
		a[i] = c - '0';
	}
	
	node ans;
	
	rep(a, 0, k + 1) rep(b, 0, k + 1)
	rep(c, 0, k + 1) rep(d, 0, k + 1) f[a][b][c][d].len = inf;
	f[0][0][0][0].len = 0;
	rep(a, 0, k + 1) rep(b, 0, k + 1)
	rep(c, 0, k + 1) rep(d, 0, k + 1) if(a + b + c + d <= k + 1 && f[a][b][c][d].len < inf) {
		int l = a * len0 + b * len1 + c * len2 + d * len3 + 1;
		
		if(l + len0 - 1 <= n) cmin(f[a + 1][b][c][d], f[a][b][c][d] + calc(l, l + len0 - 1));
		if(l + len1 - 1 <= n) cmin(f[a][b + 1][c][d], f[a][b][c][d] + calc(l, l + len1 - 1));
		if(l + len2 - 1 <= n) cmin(f[a][b][c + 1][d], f[a][b][c][d] + calc(l, l + len2 - 1));
		if(l + len3 - 1 <= n) cmin(f[a][b][c][d + 1], f[a][b][c][d] + calc(l, l + len3 - 1));
		
		if(l == n + 1 && a + b + c + d == k + 1) cmin(ans, f[a][b][c][d]);
	}
	
	ans.print();
}

bool Me;

int main() {
	
	cerr << (&Mb - &Me) / 1024.0 / 1024.0 << endl;
	
	int t = read(); while(t --) solve(); return 0;
}