#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int, int>
#define inf 0x3f3f3f3f

const int N = 2e5 + 5;
const int mod = 998244353;
int a[N];
void solve()
{
    int a, b, c;
    cin >> a >> b >> c;
    int ans = b * c, num = 1, sum = 0;
    while (num < c)
    {
        num *= 2;
        sum += a;
        ans = min(ans, sum + (c + num - 1) / num * b);
    }
    ans = min(ans, sum + (c + num - 1) / num * b);
    cout << ans << '\n';
}

signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int T = 1; cin >> T;
    while (T--) solve();
    return 0;
}