from sys import stdin


def main():
    input = lambda: stdin.readline()[:-1]
    Q = int(input())
    NK = [tuple(map(int, input().split())) for _ in [0] * Q]

    for n, k in NK:
        if k == 1:
            ans = n - 1
        else:
            x = 0
            for i in range(31):
                x += k ** i
                if x >= n:
                    ans = i
                    break
        print(ans)


main()