R=range
J=input
P=998244353
I=[0,1]
for i in R(2,5000002):I+=[(-(P//i)*I[P%i])%P]
for t in R(int(J())):
	N,S,E,s=int(J()),J(),0,0
	for i in R(N):
		s+=E+1
		if S[i]>'B':E+=1
		else:E=s*I[i+2]%P
	print(s%P)