MOD = 998244353
MOD2 = MOD * 2

def triangle(n: int) -> int:
    n %= MOD2
    res = n * (n - 1)
    res >>= 1
    return res % MOD

def solve(N: int, A: int) -> int:
    if N == 0:
        return 0
    if A == 1:
        return triangle(N)
    M = N // A
    ans = triangle(N - M)
    ans += (N % A + 1) * M
    ans += solve(M, A)
    return ans % MOD

for _ in range(int(input())):
    N, A = map(int, input().split())
    print(solve(N, A))