#include <bits/stdc++.h>
using namespace std;
#define all(v) (v).begin(),(v).end()
#define pb(a) push_back(a)
#define rep(i, n) for(int i=0;i<n;i++)
#define foa(e, v) for(auto& e : v)
using ll = long long;
const ll MOD7 = 1000000007, MOD998 = 998244353, INF = (1LL << 60);
#define dout(a) cout<<fixed<<setprecision(10)<<a<<endl;

void solve() {
    long double p;
    int k;
    cin >> p >> k;
    long double a = 1;
    long double ans = 0;
    for(int i = 1; i < k; i ++) {
        ans += a * p * (long double) i;
        a *= (long double)1 - p;
    }
    ans += a * (long double) k;
    dout(ans);
}
int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t;
    cin >> t;
    while(t --) solve();
    
    return 0;
}