import math
import sys
from collections import Counter

q = int(input())

nkq = [None] * q
for i in range(q):
    nkq[i] = list(map(int, input().split(' ')))

for nk in nkq:
    if nk[1] == 1:
        print(nk[0] -1)
    else:
        n = math.floor(math.log(nk[0] * (nk[1] - 1) + 1, nk[1]))
        print(n)