#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <iomanip>
#include <cmath>
#include <map>
using namespace std;

const int maxn = 110;

int T, n, m;
int a[maxn] = {0}, b[maxn] = {0};

int main() 
{
    ios::sync_with_stdio(0);
    cin >> T;
    while (T--) {
        cin >> n >> m;
        for (int i = 1; i <= n; ++i) {
            cin >> a[i] >> b[i];
        }
        int ans = 0x3f3f3f3f;
        for (int i = 1; i <= n; ++i) {
            int d = m / a[i];
            if (m % a[i]) d++;
            ans = min(ans, d * b[i]);
        }
        cout << ans << endl;
    }
    return 0;
}