#include<cstdio>
#include<cstring>
#include<cctype>
#include<algorithm>
#include<vector>
#define pb push_back
#define mp make_pair
#define xx first
#define yy second
#define rep(i,a,b) for(int i=(a),i##_end_=(b);i<=i##_end_;i++)
#define dwn(i,a,b) for(int i=(a),i##_end_=(b);i>=i##_end_;i--)
using namespace std;
inline int read() {
    int x=0,f=1;char c=getchar();
    for(;!isdigit(c);c=getchar()) if(c=='-') f=-1;
    for(;isdigit(c);c=getchar()) x=x*10+c-'0';
    return x*f;
}
typedef long long ll;
typedef pair<int,int> pii;
int x[110],y[110];
int main() {
    int T=read();
    while(T--) {
        int n=read(),m=read(),ans=100000;
        rep(i,1,n) {
            x[i]=read(),y[i]=read();
            ans=min(ans,((m-1)/x[i]+1)*y[i]);
        }
        printf("%d\n",ans);
    }
    return 0;
}