import sys
input=sys.stdin.readline
def main():
    Q = int(input())
    for i in range(Q):
        tmp = 1
        i = 1
        N,K = map(int,input().split())
        if K == 1:
            print(N-1)
        else:
            while tmp < N:
                tmp += K**i
                i += 1
            print(i-1)
if __name__ == '__main__':
    main()