Q = int(input())
for q in range(Q):
    A,B,C = map(int,input().split())
    if C==1:
        print(-1)
        continue
    if A < C:
        print(B)
        continue

    bit = []
    while A>0:
        bit.append(A%C)
        A //= C
    bit.reverse()
    M = len(bit)
    sum = 0
    if bit[1]==0 or bit[0]*C+bit[1]<=2*C-2:
        sum += 2
    else :
        sum += 3
    for i in range(2,M):
        if(bit[i]>0) :
            sum += 1
    sum += M-2
    print(sum*B)