#include<bits/stdc++.h>
using namespace std;
const int maxn=2e5+100;
int n,k,n0;
int a[maxn],b[maxn];
string s;
vector<int> f[10][100];
bool operator <(const vector<int> &x,const vector<int> &y) {
	if (x.size()!=y.size()) return x.size()<y.size();
	for (int i=0;i<x.size();i++) {
		if (x[i]!=y[i]) return x[i]<y[i]; 
	}
	return 0;
}
vector<int> build(int l,int r) {
	vector<int> ret;
	for (int i=r;i>=l;i--) {
		ret.push_back(a[i]);
	}
	return ret;
}
void output(vector<int> &x) {
	for (int i=x.size()-1;i>=0;i--) cout<<x[i];
	cout<<"\n";
}
int main() {
	ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	int T;cin>>T;
	while (T--) {
		cin>>n>>k;
		cin>>s;
		k++;
		for (int i=1;i<=n;i++) a[i]=s[i-1]-'0';
		n0=n/k;
		while (n0>=2&&n-n0*k<k*(k-1)/2) n0--;
		int m=n-n0*k;
		f[0][0].resize(n0);
		for (int i=1;i<=k;i++) {
			for (int j=0;j<=m;j++) {
				for (int p=0;p<=k-1&&p<=j;p++) {
					if (i==k&&j!=m) continue;
					if (f[i-1][j-p].empty()) continue;
					vector<int> wy=f[i-1][j-p];
					if (n0+p>wy.size()) wy.resize(n0+p);
					for (int q=0,r=i*n0+j;q<n0+p;q++) {
						wy[q]+=a[r-q];
					}
					for (int i=0;i<wy.size();i++) {
						if (wy[i]>=10) {
							if (i+1<wy.size()) {
								wy[i+1]+=wy[i]/10;
								wy[i]%=10;
							} else {
								wy.push_back(wy[i]/10);
								wy[i]%=10;
								break;
							}
						}
					}
					if (f[i][j].empty()||wy<f[i][j]) f[i][j]=wy;
				}
			}
		}
		output(f[k][m]);
		for (int i=0;i<=k;i++) {
			for (int j=0;j<=m;j++) {
				f[i][j].clear();
			}
		}
	}
}
/*
1
9 3
999109191
*/