#include <bits/stdc++.h>
using namespace std;

#define ll long long 
#define lll __int128
#define INF 0x3f3f3f3f
#define LNF 0x3f3f3f3f3f3f3f3fll
#define MOD 998244353
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ld long double
#define fi first
#define se second
#define all(a) a.begin(), a.end()

#define N 5050

int main() {
#ifdef TEST
    freopen("zz.in", "r+", stdin);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t; cin >> t;
    while (t --) {
        int a, b, c; cin >> a >> b >> c;
        ll rr = 1;
        ll cur = 0;
        ll res = LNF;
        while (rr <= c * 2) {
            res = min(res, cur + (c + rr - 1) / rr * b);
            rr <<= 1;
            cur += a;
        }
        cout << res << '\n';
    }
}