R=range
I=input
P=998244353
for t in R(int(I())):
	N,S,E,s=int(I()),I(),0,0
	for i in R(N):
		s+=E+1
		if S[i]>'B':E+=1
		else:E=s*pow(i+2,-1,P)%P
	print(s%P)