using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
using System.Security.Cryptography;
using Microsoft.VisualBasic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    static long[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var q = NN;
        var ans = new int[q];
        for (var u = 0; u < q; ++u)
        {
            var c = NList;
            var (n, k) = (c[0], c[1]);
            var mul = 1L;
            --ans[u];
            while (n > 0)
            {
                ++ans[u];
                n -= mul;
                mul *= k;
            }
        }
        WriteLine(string.Join("\n", ans));
    }
}