#include<iostream>
#include<atcoder/modint>
using namespace std;
using mint=atcoder::modint998244353;
long N,X;
main()
{
	int T;cin>>T;
	for(;T--;)
	{
		cin>>N>>X;
		if(X%2==1)cout<<mint((N+1)/2).val()<<"\n";
		else
		{
			mint ans=0;
			if(X+1<=N/X)
			{
				long t=X*(X+1);
				ans+=N/t*(X/2*(X+2));
				N%=t;
			}
			if(N<=X)ans+=N/2;
			else
			{
				N-=X;
				ans+=X/2;
				if(N<=X)ans+=(N+1)/2;
				else
				{
					N-=X;
					ans+=X/2;
					long t=N/X;
					ans+=2*t;
					ans+=t;
					ans+=(t+1)/2;
					N%=X;
					//t,t+1 -> O
					//t,t-2,t-4,...
					if(N<=t+1)
					{
						if(t%2==0)ans+=(N+1)/2;
						else ans+=N/2;
					}
					else
					{
						ans+=(t+2)/2;
						N-=t+1;
						ans+=(N+1)/2;
					}
				}
			}
			cout<<ans.val()<<"\n";
		}
	}
}