#897
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())
        while tmp < N:
            tmp += K**i
            i += 1
        print(i-1)
if __name__ == '__main__':
    main()