#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <typename T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <typename T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct IOST {
	IOST() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(20);
	}
} IOST;

using mint = atcoder::modint998244353;

mint calc(ll n, ll a) {
	if (n == 1) return 0;
	if (n < a) return mint(n) * (n - 1) / 2;
	ll bn = (n / a);
	return mint(n - bn) * (n - bn - 1) / 2 + calc(bn, a) +
		   bn * (n - bn * a + 1);
}

void solve() {
	ll n, a;
	cin >> n >> a;
	cout << calc(n, a).val() << "\n";
}

int main() {
	int t = 1;
	cin >> t;
	rep(i, 0, t) solve();
}