#include <bits/stdc++.h>

int ri() {
	int n;
	scanf("%d", &n);
	return n;
}

int64_t solve(int a, int b, int c) {
	if (c == 1) return -1;
	std::vector<int> keta;
	for (; a; a /= c) keta.push_back(a % c);
	std::reverse(keta.begin(), keta.end());
	if (keta.size() == 1) return b;
	int64_t res = 0;
	if (keta[0] == 1 && keta[1] < c - 1) res += 2;
	else res += !!keta[1] + 2;
	int head = 2;
	for (; head < (int) keta.size(); head++) {
		if (keta[head]) res++;
		res++;
	}
	return res * b;
}

int main() {
	int q = ri();
	for (int i = 0; i < q; i++) {
		int a = ri(), b = ri(), c = ri();
		std::cout << solve(a, b, c) << std::endl;
	}
	
	return 0;
}