//这回只花了114514min就打完了。
//真好。记得多手造几组。
#include <bits/stdc++.h>
//#define int long long
//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define pai 3.141592653589793238462643383279502884197169399375105820
#define MOD 1000000007
#define eps 0.00000001
inline int min(int a,int b) {return a<b?a:b;}
inline int max(int a,int b) {return a>b?a:b;}
#define ULL unsigned long long
#define LL long long
#define INF 0x3f3f3f3f
#define INF_LL 0x3f3f3f3f3f3f3f3f
static char buf[1000000],*paa=buf,*pd=buf;
static char buf2[1000000],*pp=buf2;
#define getchar() paa==pd&&(pd=(paa=buf)+fread(buf,1,1000000,stdin),paa==pd)?EOF:*paa++
inline void pc(char ch){
	if(pp-buf2==1000000) fwrite(buf2,1,1000000,stdout),pp=buf2;
	*pp++=ch;
}
inline void pcc(){
	fwrite(buf2,1,pp-buf2,stdout);
	pp=buf2;
}
inline int read(void) {
	int w=1;
	register int x(0);register char c(getchar());
	while(c<'0'||c>'9') {if(c=='-') w=-1;c=getchar();}
	while(c>='0'&&c<='9') x=(x<<1)+(x<<3)+(c^48),c=getchar();
	return w*x;
}
void write(int x) {
	if(x<0) pc('-'),x=-x;
	static int sta[20];
	int top=0;
	do {
		sta[top++]=x%10,x/=10;
	} while(x);
	while(top) pc(sta[--top]+48);
}
void we(int x) {
	write(x);
	pc('\n');
}
inline bool cmp_xi(int a,int b) {return a<b;}
inline bool cmp_da(int a,int b) {return a>b;}
int T,N,anss,K,nn,a[10];
char su[100009],as[100009],ss[100009];
char s[200009];
inline void tryy(int ma,int mi) {
	memcpy(ss,su,sizeof(char)*(ma+1));
	int l=1,r=a[1];
	for(int j=l;j<=r;j++) {
		ss[r-j]+=s[j]-'0';
	}	
	if(ss[ma]>as[ma]) return;
	if(ss[ma]==as[ma]&&ss[ma-1]>as[ma-1]) return;	
	for(int i=0;i<=ma;i++) {
		ss[i+1]+=ss[i]/10;
		ss[i]%=10;
	}
	for(int i=ma;i>=0;i--) {
		if(ss[i]>as[i]) {
			return;
		}
		if(ss[i]<as[i]) {
			memcpy(as,ss,sizeof(char)*(i+1));
			return;
		}
	}
}
void dfs(int n,int f,int ma,int mi) {
	if((n-1+f-1)/f>ma||(n-1)/f<mi) return;
	if(f==1) {
		tryy(ma,mi);
		return;
	}
	for(int j=n-mi+1;j<n;j++) su[n-1-j]+=s[j]-'0';
	for(int i=n-mi;i>=n-ma&&i>=1;i--) {
		su[n-1-i]+=s[i]-'0';
		if(su[ma]>as[ma]) continue;
		if(su[ma]==as[ma]&&su[ma-1]>as[ma-1]) continue;
		a[f-1]=i-1;
		dfs(i,f-1,ma,mi);
	}
	for(int j=std::max(n-ma,1);j<n;j++) su[n-1-j]-=s[j]-'0';
}
signed main(void) {
//    freopen("m.in","r",stdin);
//    freopen("m.out","w",stdout);
    scanf("%d",&T);
    while(T--) {
    	scanf("%d %d %s",&N,&K,s+1);
    	int ma=(N+K)/(K+1)+1,mi=N-K*ma;
    	if(mi<1) mi=1;
    	for(int i=0;i<=ma;i++) as[i]=9;
    	dfs(N+1,K+1,ma,mi);
    	bool ff=0;
    	for(int i=ma;i>=0;i--) {
    		if(as[i]) {
    			for(int j=i;j>=0;j--) printf("%d",as[j]);
    			ff=1;
    			break;
			}
		}
		if(!ff) printf("0");
		printf("\n");
	}
    return 0;
}