// By AmmarDab3an 

#include "bits/stdc++.h"

using namespace std;

#define int int64_t
#define ll  int64_t

// typedef unsigned int        uint;
// typedef long long int       ll;
// typedef unsigned long long  ull;
typedef pair<int, int>    pii;
typedef pair<ll, ll>      pll;
typedef pair<int, pii>    iii;
typedef pair<ll, pll>     lll;
typedef vector<int>       vi;
typedef vector<ll>        vl;
typedef vector<pii>       vpii;
typedef vector<pll>       vpll;

#define endl '\n'
#define fastIO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define freopenI freopen("input.txt", "r", stdin);
#define freopenO freopen("output.txt", "w", stdout);

const int INF = 0x3f3f3f3f;
const ll INFLL = 0x3f3f3f3f3f3f3f3f;
const int MOD = 1e9 + 7;
const double EPS = 1e-9;
const double  PI = acos(-1);

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
int rand(int x, int y) {
	return uniform_int_distribution<int>(x, y)(rng);
}

int mul(int a, int b){
	int ret = (1ll * (a%MOD) * (b%MOD)) % MOD;
	return (ret+MOD)%MOD;
}
 
int add(int a, int b){
	int ret = (1ll * (a%MOD) + (b%MOD)) % MOD;
	return (ret+MOD)%MOD;
}
 
int pow_exp(int n, int p){
	if(!p) return 1;
	if(p&1) return mul(n, pow_exp(n, p-1));
	int tmp = pow_exp(n, p/2);
	return mul(tmp, tmp);
}

int inv(int x){
	return pow_exp(x, MOD-2);
}
 
const int  MAX = 2e5 + 10;
const int NMAX = 2e5 + 10;
const int MMAX = 2e5 + 10;
const int LOG_MAX = ceil(log2(double(NMAX)));
const int BLOCK = ceil(sqrt(double(NMAX)));

int fac[NMAX], ifac[NMAX];

void init(){
	
	fac[0] = 1;
	for(int i = 1; i < NMAX; i++){
		fac[i] = mul(fac[i-1], i);
	}
	
	ifac[NMAX-1] = inv(fac[NMAX-1]);
	for(int i = NMAX-2; i >= 0; i--){
		ifac[i] = mul(ifac[i+1], i+1);
	}
}

int choose(int n, int c){
	assert(n >= c);
	return mul(fac[n], mul(ifac[c], ifac[n-c]));
}

string ad(string a, string b){
	
	string ret;
	
	// reverse(a.begin(), a.end());
	// reverse(b.begin(), b.end());
	
	int carry = 0;
	
	while(!a.empty() && !b.empty()){
		
		int d = a.back()-'0' + b.back()-'0' + carry;
		carry = d/10;
		d %= 10;
		
		ret.push_back('0' + d);
		a.pop_back();
		b.pop_back();
	}
	
	while(!a.empty()){
		int d = a.back()-'0' + carry;
		carry = d/10;
		d %= 10;
		ret.push_back('0' + d);
		a.pop_back();
	}
	
	while(!b.empty()){
		int d = b.back()-'0' + carry;
		carry = d/10;
		d %= 10;
		ret.push_back('0' + d);
		b.pop_back();
	}
	
	if(carry) ret.push_back('0' + carry);
	
	reverse(ret.begin(), ret.end());
	
	return ret;
}

string mn(const string &a, const string &b){
	if(a.size() != b.size()){
		return a.size() < b.size() ? a : b;
	}	
	else{
		return min(a, b);
	}
}

int32_t main(){
    
    fastIO;
    
#ifdef LOCAL
    freopenI;
    freopenO;
#endif

    // freopen("name.in", "r", stdin);
    
	// init();
	
    int t; cin >> t; while(t--){

		int n, k;
		cin >> n >> k;
		k++;
		
		string num;
		cin >> num;
		
		n = num.size();
		
		int m = n/k;
		vi tmp(k, m);
		for(int i = 0; i < (n%k); i++){
			tmp[i]++;
		}
		
		sort(tmp.begin(), tmp.end());
		
		// for(auto e : tmp) cout << e << ' '; cout << endl;
		// continue;
		
		string ans = string(n, '9');
		
		do {
			
			string cur = "0";
				
			int i = 0;
			for(auto e : tmp){
				string ccur = num.substr(i, e);
				cur = ad(cur, ccur);
				i += e;
				// cout << ccur << endl;
			}
			
			assert(i==n);
			
			ans = mn(ans, cur);
			
		} while(next_permutation(tmp.begin(), tmp.end()));
		
		cout << ans << endl;
    }	
}