#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll mod = 998244353;
constexpr ll twoinv = 499122177;
ll t,n,a;
ll f(ll i){
    if(i == n) return 0;
    if(i * a > n) return (n - i) % mod;
    return (f(a * i) + 1) % mod;
}
int main(){
    cin >> t;
    while(t--){
        cin >> n >> a;
        if(a == 1){
            cout << ((((n % mod) * ((n - 1) % mod)) % mod) * twoinv ) % mod<< endl;
            continue;
        }
        ll ans = 0;
        for(ll i = 1; i <= n; i++){
            ans += f(i);
        }
        cout << ans << endl;
    }
}