#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
constexpr ll mod = 998244353;
constexpr ll twoinv = 499122177;
#define fast cin.tie(nullptr); ios_base::sync_with_stdio(false)

ll t,n,a;
mint s(ll x){
  if(a == 1){
  	mint ans = n;
  	ans *= n - 1;
  	ans /= 2;
  	return ans;
  }
  if(x <= 1) return 0;
  ll b = x / a,c = x - a * b;
  mint res = (c + 1);
  res *= b;
  mint pl = (x - b - 1);
  pl *= x - b;
  pl /= 2;
  return res + pl + s(b);
}
int main() {
	fast;
    cin >> t;
    while(t--){
        cin >> n >> a;
        cout << s(n).val() << endl;
    }
}