#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<map>
using namespace std;
int main(){
    int test;
    cin>>test;
    int n,m;
//    while(test--){
        while(test--&&cin>>n>>m){
            int x[n],y[n];
            int v;
            for(int i=0;i<n;i++){
                cin>>x[i]>>y[i];
            }
            if(n==1){
                if(m%x[0]==0){
                    cout<<y[0]*m/x[0]<<endl;
                }
                else{
                    cout<<y[0]*(m/x[0]+1)<<endl;
                }
            }
            else{
                int minn=10050;
                for(int i=0;i<n;i++){
                    if(m%x[i]==0){
                        v=y[i]*m/x[i];
                    }
                    else{
                        v=y[i]*(m/x[i]+1);
                    }
                    if(v<minn) minn=v;
                }
                cout<<minn<<endl;
            }
        /*    int dp[10050];
            for(int i=0;i<10050;i++){
                dp[i]=0;
            }
            for(int i=0;i<n;i++){
                for(int j=x[i];j<=m;j++){
                    dp[j]=max(dp[j],dp[j-x[i]]+y[i]);
                }
            }
            cout<<dp[m]<<endl;*/
            
        }
//}
    return 0;
}