#include<iostream>

#include<cstdio>

#include<algorithm>

using namespace std;

#define int long long

int t;

int N;

int A[];

int B[];

int dp[][];

double ans =0.0;

const int INF = 1e18;

signed main()

{

    scanf("%lld",&t);

    while(t--){

        int tmp =;

        scanf("%lld",&N);

        for(int i=;i<=N;i++){

            scanf("%lld%lld",&A[i],&B[i]);

            tmp+=A[i]*B[i];

            A[i]*=;

            for(int j=;j<;j++){

                dp[][j]=dp[i][j]=INF;

            }

        }

        dp[][]=tmp;

        int x ;

        for(int i=;i<=N;i++){

            for(int j=;j<;j++){

                x= (j-A[i]/+)%;

                dp[i][j]=min(dp[i-][x]-(A[i]/10ll)*B[i]+j*10ll-x*10ll+((x+A[i]/10ll)/400ll)*3000ll,dp[i-][j]);

            }

        }

        tmp = 1e18;

        for(int j=;j<;j++){

            tmp = min(tmp,dp[N][j]);

        }

        printf("%.1f\n",tmp*0.1);

    }

}