import sys

def input():
    return sys.stdin.readline()[:-1]

def main():
    Q = int(input())
    for _ in range(Q):
        N, K = map(int,input().split())
        if K == 1:
            print(N-1)
        else:
            ans = -1
            t = 0
            while t < N:
                ans += 1
                t += K**ans
            print(ans)

if __name__ == '__main__':
    main()