#include <bits/stdc++.h>

int main()
{
	int Q;
	scanf("%d", &Q);
	for (int i{}; i < Q; i++)
	{
		int64_t N, K;
		scanf("%lld%lld", &N, &K);
		if (K == 1)
		{
			printf("%lld\n", N - 1);
			continue;
		}
		int64_t ans{-1}, pow{1ll};
		while (N > 0)
		{
			N = std::max(N - pow, (int64_t)0);
			pow *= K;
			ans++;
		}
		printf("%lld\n", ans);
	}

	return 0;
}