import sys
input = sys.stdin.readline

from itertools import product

N=10
M=1

A=product(range(M),repeat=N)

ANS=0

for X in A:
    Y=list(X)
    score=0
    for i in range(N):
        for j in range(i+1,N):
            score+=(Y[i]+Y[j])%M

    #print(score)

    ANS+=score

#print(ANS)
#print(ANS/(M**N))

mod=998244353

T=int(input())

for tests in range(T):
    N,M=list(map(int,input().split()))

    ANS=N*(N-1)//2

    ANS=ANS*(M-1)*pow(M,N,mod)*pow(2,mod-2,mod)%mod

    print(ANS)