#include<bits/stdc++.h>
#define pp printf("\n")
#define pb push_back
using namespace std;
int T,n,k,a;
char s[200001];
int ans[200001],c[200001],d[200001],la,lc,ld;
int b[10];
void jia()
{
    for (int i=1;i<=max(lc,ld);i++)
    {
        d[i]=d[i]+c[i];
        d[i+1]+=d[i]/10;
        d[i]%=10;
    }
    ld=max(lc,ld);
    ld+=(d[ld+1]>0);
}
void minn()
{
    int bz=0;
    if (ld>la)return;
    for (int i=la;i>=1;i--)if (ans[i]!=d[i])
    {
        bz=(ans[i]>d[i]);
        break;
    }
    if (ld<la||(ld==la&&bz==1))
    {
        la=ld;
        for (int i=1;i<=la;i++)ans[i]=d[i];
    }
}
void dg(int x)
{
    if (x==k)
    {
        b[x+1]=n;
        if (n-b[x]+1>=a+3)return;
        for (int i=1;i<=k+1;i++)
        {
            for (int j=b[i];j>b[i-1];j--)c[++lc]=(s[j]-'0');
            jia();
            for (int j=1;j<=lc;j++)c[j]=0;
            lc=0;
        }
        minn();
        for (int j=1;j<=ld;j++)d[j]=0;
        ld=0;
        return;
    }
    for (int i=max(1,a-1);i<=(a+1);i++)
    {
        if (b[x]+i<=n)
        {
            b[x+1]=b[x]+i;
            dg(x+1);
        }
    }
}
int main()
{
    scanf("%d",&T);
    while (T--)
    {
        scanf("%d %d",&n,&k);
        scanf("%s",s+1);
        la=n+1;
        b[0]=0;
        a=(n+k)/(k+1);
        dg(0);
        for (int i=la;i>=1;i--)printf("%d",ans[i]);pp;
    }
}