#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
const ll INF=2e18;
const int maxn=100;
const int maxm=10000;

ll n;
ll s[maxn+50];
ll f[maxn+50];
ll dp[maxm+50];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	int TC=1;
	cin >> TC;
	for (;TC--;){
		cin >> n;
		for (int i=1;i<=n;i++){
			cin >> s[i];
			double t;
			cin >> t;
			f[i]=(ll)(t*100+0.5);
		}
		
		ll sumf=0;
		for (int i=1;i<=n;i++) sumf+=f[i];
		ll ans=0;
		for (ll F=0;F<=sumf;F++){
			if (F*F>10000*(n+2)) break;
			for (ll i=0;i<=F;i++) dp[i]=-INF;
			dp[0]=0;
			for (int i=1;i<=n;i++){
				if (f[i]>F) continue;
				ll val=s[i]*(10000-f[i]*(F-f[i]));
				for (int j=F-f[i];j>=0;j--){
					dp[j+f[i]]=max(dp[j+f[i]],dp[j]+val);
				}
			}
			ans=max(ans,dp[F]);
		}
		ll fz=ans/10000;
		ll fm=ans%10000;
		cout << fz << "." << setw(4) << setfill('0') << fm << "00000" << "\n";
	}
	return 0;	
}