#include <iostream>
#include <vector>
#include <cassert>

using namespace std;
using ll = long long;

ll mod_pow (ll a, ll x, ll MOD) {
    assert(0 <= x);
    if (MOD <= abs(a)) a %= MOD;
    if (a < 0) a += MOD;

    ll res = 1;
    ll base = a;

    while (0 < x) {
        if (0 < (x & 1)) {
            res *= base;
            res %= MOD;
        }
        base *= base;
        base %= MOD;
        x >>= 1;
    }

    return res;
}

ll mod_inv (ll x, ll MOD) {
    return mod_pow(x, MOD-2, MOD);
}

void solve (int N, vector<pair<int, int>>& z) {
    // 頑張って変形すると累積和でOKになる。
    const ll MOD = 998244353;

    vector<ll> cum(N+1), cum_inv(N+1), cum_re(N+1), cum_im(N+1);
    for (int i = 0; i < N; i++) {
        ll v = ((1LL * z[i].first * z[i].first) + (1LL * z[i].second * z[i].second)) % MOD;
        cum[i+1] = (cum[i] + v) % MOD;
        cum_inv[i+1] = (cum_inv[i] + mod_inv(v, MOD)) % MOD;

        // 分子に共役が乗ってる方を計算する
        ll v_num_re = ((1LL * z[i].first * z[i].first) - (1LL * z[i].second * z[i].second)) % MOD;
        ll v_num_im = (-2LL * z[i].first * z[i].second) % MOD;

        if (v_num_re < 0) v_num_re += MOD;
        if (v_num_im < 0) v_num_im += MOD;
        v_num_re *= mod_inv(v, MOD);
        v_num_im *= mod_inv(v, MOD);
        v_num_re %= MOD;
        v_num_im %= MOD;

        cum_re[i+1] = (cum_re[i] + v_num_re) % MOD;
        cum_im[i+1] = (cum_im[i] + v_num_im) % MOD;
    }

    ll ans = 0;
    for (int i = 0; i < N-1; i++) {
        ll v = ((1LL * z[i].first * z[i].first) + (1LL * z[i].second * z[i].second)) % MOD;

        ll add = 0;
        add += (v * (cum_inv[N] - cum_inv[i+1])) % MOD;
        add %= MOD;

        add += (mod_inv(v, MOD) * (cum[N] - cum[i+1])) % MOD;
        add %= MOD;

        ll v_num_re = ((1LL * z[i].first * z[i].first) - (1LL * z[i].second * z[i].second)) % MOD;
        ll v_num_im = (-2LL * z[i].first * z[i].second) % MOD;
        if (v_num_re < 0) v_num_re += MOD;
        if (v_num_im < 0) v_num_im += MOD;

        v_num_re *= mod_inv(v, MOD);
        v_num_im *= mod_inv(v, MOD);
        v_num_re %= MOD;
        v_num_im %= MOD;

        add += -2 * v_num_re * (cum_re[N] - cum_re[i+1]) % MOD;
        add %= MOD;
        add += -2 * v_num_im * (cum_im[N] - cum_im[i+1]) % MOD; // マイナスは打ち消される。
        add %= MOD;

        if (add < 0) add += MOD;

        ans += add;
        ans %= MOD;
    }

    cout << ans << "\n";
}

int main () {
    int T; cin >> T;
    for (int t = 0; t < T; t++) {
        int N; cin >> N;
        vector<pair<int, int>> z(N);
        for (int i = 0; i < N; i++) {
            int x, y; cin >> x >> y;
            z[i] = make_pair(x, y);
        }

        solve(N, z);
    }
}