#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#define display(x) cerr << #x << " = " << x << endl;
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define display(x) {}
#define eprintf(...) do {} while(0)
#endif

template<typename T> bool chmin(T &a, const T &b) { return a > b ? a = b, true : false; }
template<typename T> bool chmax(T &a, const T &b) { return a < b ? a = b, true : false; }
template<typename T>
ostream& operator << (ostream& out, const vector<T> &v) {
    int n = v.size();
    out << "{";
    for(int i = 0; i < n; ++i) {
        if(i) out << ", ";
        out << v[i];
    }
    return out << "}";
}
template<typename A, typename B>
ostream& operator << (ostream& out, const pair<A, B> &v) {
    return out << "(" << v.first << ", " << v.second << ")";
}

typedef long long LL;
typedef pair<int, int> pii;

void solve() {
    int n, m;
    cin >> n >> m;
    int ans = 100 * 100000 + 5;
    for(int i = 0; i < n; ++i) {
        int x, y; cin >> x >> y;
        chmin(ans, (m + x - 1) / x * y);
    }
    cout << ans << '\n';
}

int main() {
#ifndef LOCAL
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
#endif
    int T; cin >> T;
    while(T--) solve();
    return 0;
}