import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int q = Integer.parseInt(br.readLine());
		for (int i = 0; i < q; i++) {
			String[] sa = br.readLine().split(" ");
			long n = Integer.parseInt(sa[0]);
			long k = Integer.parseInt(sa[1]);
			if (k == 1) {
				System.out.println(n - 1);
			} else {
				long sum = 0;
				for (int j = 0; j < 40; j++) {
					long b = (long) Math.pow(k, j);
					sum += b;
					if (sum >= n) {
						System.out.println(j);
						break;
					}
				}
			}
		}
		br.close();
	}
}