#include <cstdio>
#include <cstring>
using namespace std;

typedef long long ll;
int T; ll x,y,a,b,c,ans;

ll min(ll x,ll y) { return x < y ? x : y; }

void read(int &x)
{
	char c = getchar(); x = 0;
	while(c < '0' || c > '9') c = getchar();
	while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
}

int main()
{
	for(scanf("%d",&T);T--;)
	{
		scanf("%lld%lld%lld",&a,&b,&c),
		ans = 1ll * c * b, x = 1ll, y = 0ll;
		
		while(x < c)
			x *= 2, y += a, ans = min(ans,y + 1ll * b * ((c - 1) / x + 1));
		printf("%lld\n",ans);
	}
	
	return 0;
}