#include <bit/stdc++.h>

using namespace std;

int main(int argc, char const *argv[]) {
    const double PI = atan(1.0) * 4;
    int n;
    double r;
    for (cin >> n; cin >> r, n--;) {
        cout << setiosflags(ios::fixed) << setprecision(6) << PI * r * r << endl;
    }
    return 0;
}