#include <bits/stdc++.h>

#define llong long long

using namespace std;

typedef vector<int> big;

const int MAXN = (int) 5e3 + 7;
const int INF = (int) 2e9 + 7;

int t, n;
long long path[MAXN][MAXN];

double prob[MAXN][MAXN];
double expect[MAXN][MAXN];

int main() {
  #ifdef LOCAL
  freopen("in", "r", stdin);
  #endif

  ios_base::sync_with_stdio(0);

  cin >> t;
  while (t--) {
    cin >> n;
    for (int i = 1; i <= n + 1; i++) {
      for (int j = 1; j <= n + 1; j++) {
        prob[i][j] = 0.0;
        expect[i][j] = 0.0;
      }
    }

    prob[1][1] = 1.0;
    expect[1][1] = 0.0;
    for (int i = 1; i <= n; i++) {
      for (int j = 1; j <= i; j++) {
        int d, dr;
        cin >> d >> dr;
        if (d < dr) {
          prob[i + 1][j] += prob[i][j];
          expect[i + 1][j] += expect[i][j] + prob[i][j] * d;
        }
        else if (dr < d) {
          prob[i + 1][j + 1] += prob[i][j];
          expect[i + 1][j + 1] += expect[i][j] + prob[i][j] * dr;
        }
        else {
          double cur = expect[i][j] + prob[i][j] * d;
          cur /= 2;

          prob[i + 1][j] += prob[i][j] * 0.5;
          prob[i + 1][j + 1] += prob[i][j] * 0.5;

          expect[i + 1][j] += cur;
          expect[i + 1][j + 1] += cur;
        }
      }
    }
    double ans = 0.0;
    for (int i = 1; i <= n + 1; i++) {
      ans += expect[n + 1][i];
    }
    cout << fixed << setprecision(10) << ans << "\n";
  }
  return 0;
}