#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll mod = 998244353;
constexpr ll twoinv = 499122177;
#define fast cin.tie(nullptr); ios_base::sync_with_stdio(false)
ll modpow(ll base, ll exp) {
    if (!exp) return 1;
    ll res = modpow(base, exp / 2);
    res = (res * res) % mod;
    if (exp % 2) res = (res * base) % mod;
    return res;
}
ll inv(ll x,ll mod){
    return modpow(x,mod - 2);
}
ll digsum(ll n,ll a){
    ll res = 0;
    while(n){
        res += n % a;
        n /= a;
    }
    return res;
}
ll sum(ll n,ll a){
    if(a == 1){
        return ((((n % mod) * ((n - 1) % mod)) % mod) * twoinv) % mod;
    }
    ll k = 0,power = 1,ans = 0;
    while(power <= n){
        ll f = (n / power) % mod + digsum(n % power,a) % mod + k;
        f %= mod;
        ans += f * ((n / power - n / (power*a))% mod) % mod;
        ans %= mod;
        if(power > n / a) break;
        power *= a;
        k++;
    }
    ll dec = (n% mod) * ((n + 1) %mod) % mod * twoinv % mod;
    return ((ans-dec)% mod + mod) % mod; 
}
ll t,n,a;
int main() {
	fast;
    cin >> t;
    while(t--){
        cin >> n >> a;
        cout << sum(n,a) << endl;
    }
}