#include <iostream>
#include <algorithm>
#include <cstdio>
#include <vector>
#include <map>
#include <cstring>
#include <string>

using namespace std;

string A, B;
int n, m, L;
int a[1111111], b[31111], c[31111], ans[31111];
int pcalc[7][7][7];

int main() {
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	int t;
	cin >> t;
	for (int ca = 0; ca < 7; ca++) {
		for (int cb = 0; cb < 7; cb++) {
			for (int cc = 0; cc < 7; cc++) {
				for (int x = 0; x < 7; x++) {
					if ((ca + x * cb) % 7 == cc) {
						pcalc[ca][cb][cc] = x;
						break;
					}
				}
			}
		}
	}
	while (t) {
		t--;
		cin >> A >> B >> L;
		memset(a, 0, sizeof(a));
		memset(b, 0, sizeof(b));
		memset(c, 0, sizeof(c));
		memset(ans, 0, sizeof(ans));
			
		n = A.size();
		m = B.size();
		
		for (int i = 0; i < n; i++) {
			a[i] = A[n - i - 1] - '0';
		}
		
		for (int i = 0; i < m; i++) {
			b[i] = B[m - i - 1] - '0';
		}
		
		int zeroes = 0;
		while (b[zeroes] == 0) {
			zeroes++;
		}		
		n -= zeroes;
		m -= zeroes;
		for (int i = 0; i < n; i++) {
			a[i] = a[i + zeroes];
		}	
		for (int i = n; i < n + zeroes; i++) {
			a[i] = 0;
		}
		for (int i = 0; i < m; i++) {
			b[i] = b[i + zeroes];
		}
		for (int i = m; i < m + zeroes; i++) {
			b[i] = 0;
		}
		
		for (int i = 0; i < L; i++) {	
			c[i + 1] += c[i] / 7;
			c[i] %= 7;
					
			int already = c[i];
			int goal = a[i];
			int have = b[0];
			int what = pcalc[already][have][goal]; 		
			ans[i] = what;
			for (int j = 0; (i + j) < L; j++) {
				c[i + j] += b[j] * what; 
			}
			c[i + 1] += c[i] / 7;
			c[i] %= 7;				
		}
		
		int p = L - 1;
		while (!ans[p] && p) {
			p--;
		}
		
		for (; p + 1; p--) {
			cout << ans[p];
		}
		cout << endl;
	}
	
	return 0;
}