// #pragma GCC target("avx") // #pragma GCC optimize("O3") // #pragma GCC optimize("unroll-loops") #include using namespace std; #define rep(i,n) for(int i = 0; i < (int)n; i++) #define FOR(n) for(int i = 0; i < (int)n; i++) #define repi(i,a,b) for(int i = (int)a; i < (int)b; i++) #define all(x) x.begin(),x.end() //#define mp make_pair #define vi vector #define vvi vector #define vvvi vector #define vvvvi vector #define pii pair #define vpii vector> template void chmax(T &a, const T &b) {a = (a > b? a : b);} template void chmin(T &a, const T &b) {a = (a < b? a : b);} using ll = long long; using ld = long double; using ull = unsigned long long; const ll INF = numeric_limits::max() / 2; const ld pi = 3.1415926535897932384626433832795028; const ll mod = 998244353; int dx[] = {1, 0, -1, 0, -1, -1, 1, 1}; int dy[] = {0, 1, 0, -1, -1, 1, -1, 1}; #define int long long void solve() { ld p, k; cin >> p >> k; ld prob = 1; ld ans = 0; repi(i, 1, k+1) { ld now = prob*p; ans += now*i; prob -= now; } ans += k*prob; cout << ans << endl; } signed main() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(10); int t; cin >> t; while(t--) solve(); return 0; }