/* -*- coding: utf-8 -*-
 *
 * 915.cc:  No.915 Plus Or Multiple Operation - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

typedef long long ll;

/* global variables */

/* subroutines */

/* main */

int main() {
  int q;
  scanf("%d", &q);

  while (q--) {
    int a, b, c;
    scanf("%d%d%d", &a, &b, &c);

    if (c == 1) puts("-1");
    else {
      ll cc = (ll)c * c;
      int cnt = 0;
      while (a > 0) {
	if (a >= c && a <= (c - 1) * 2)
	  cnt += 2, a = 0;
	else {
	  if (a % c > 0) cnt++;
	  a /= c;
	  if (a > 0) cnt++;
	}
      }
      printf("%lld\n", (ll)cnt * b);
    }
  }

  return 0;
}