q = int(input())
nk = [[int(i) for i in input().split()] for j in range(q)]

for i in range(q):
    n,k = nk[i]
    if k == 1:
        print(n-1)
    else:
        tmp = 1
        now = 1
        cnt = 0
        while tmp < n:
            now *= k
            cnt += 1
            tmp += now
        print(cnt)