#include <bits/stdc++.h>
using namespace std;
int a[15]={6,2,5,5,4,5,6,3,7,6};
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int len;
        char c[100005];
        scanf("%d%s",&len,c);
        int sum=0;
        for(int i=0;i<len;i++)
            sum+=a[c[i]-‘0‘];
        for(int i=0;i<len;i++) {
            for(int j=9;j>=0;j--) {
                int lefts = sum-a[j];
                int leftn = len-i-1;
                //printf("%d\n",lefts);
                if(leftn*2<=lefts&&lefts<=leftn*7) {
                    putchar(‘0‘+j);
                    sum = lefts;
                    break;
                }
            }
        }
        puts("");
    }
    return 0;
}