import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;


public class f {

    public static void main(String[] args) throws NumberFormatException, IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int T = Integer.parseInt(br.readLine());
        StringTokenizer st;

        for (int t = 1; t <= T; t++) {
            int N = Integer.parseInt(br.readLine());
            int[][] arr = new int[N][2];
            for (int i = 0; i < arr.length; i++) {
                st = new StringTokenizer(br.readLine());
                arr[i][0] = Integer.parseInt(st.nextToken());
                arr[i][1] = Integer.parseInt(st.nextToken());
            }

            long res = 0;
            for (int i = 0; i < arr.length-1; i++) {
                if((arr[i][0]+10)*arr[i][1] > arr[i][0]*arr[i+1][1]){
                    arr[i+1][0] += arr[i][0];
                }
                else{
                    res += (arr[i][0]+10)*arr[i][1];
                }
            }
            res += (arr[arr.length-1][0]+10) * arr[arr.length-1][1];

            System.out.println(res);
        }
    }
}