#include<bits/stdc++.h>
#define clr(x) memset(x,0,sizeof(x))
#define clrmax(x) memset(x,0x3f3f3f3f,sizeof(x))
#define clrmin(x) memset(x,-0x3f3f3f3f,sizeof(x))
#define pb push_back
#define LL long long
#define mod 1000000007
#define mp make_pair
using namespace std;
typedef pair<int,int> pii;
const int N = 1e2+10;
const int M = 1e6+10;
int T,n,m,k,s;
int x[N],y[N];
int main(){
    scanf("%d",&T);
    while(T--){
        scanf("%d%d",&n,&m);
        for(int i=1;i<=n;i++) scanf("%d%d",x+i,y+i);
        int minx = 0x3f3f3f3f,nx;
        for(int i=1;i<=n;i++){
            nx = ((m - 1) / x[i] + 1) * y[i];
            if(nx < minx){
                minx = nx;
            }
        }
        printf("%d\n",minx);
    }
    return 0;
}