Q = int(input())
dep = []
for _ in range(Q):
    n,k = map(int,input().split())
    depth = 0
    n = n - 1 # 最初のノードを摘出
    if k == 1:
        dep.append(n)
    else:
        while n > 0:
            depth += 1
            n -= k**(depth)

        dep.append(depth)
for i in dep:
    print(i)