#include <bits/stdc++.h>
using namespace std;
using int64 = long long;
const int64 MOD = 998244353;
int64 mod_mul(int64 a, int64 b, int64 mod = MOD) {
    return (__int128)a * b % mod;
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    int T;
    cin >> T;
    const int64 INV2 = (MOD + 1) / 2;
    while (T--) {
        int64 N, A;
        cin >> N >> A;
        int64 ans = 0;
        if (A == 1) {
            int64 nmod = N % MOD;
            ans = mod_mul(mod_mul(nmod, (nmod - 1 + MOD) % MOD), INV2);
        } else {
            int64 cur = N;
            while (cur > 0) {
                if (cur < A) {
                    int64 cmod = cur % MOD;
                    int64 term = mod_mul(mod_mul((cmod - 1 + MOD) % MOD, cmod), INV2);
                    ans = (ans + term) % MOD;
                    break;
                }
                int64 m = cur / A;
                int64 r = cur % A;
                int64 term1 = mod_mul(m % MOD, (r + 1) % MOD);
                ans = (ans + term1) % MOD;
                int64 D = cur - m;
                int64 D_mod = D % MOD;
                int64 term2 = mod_mul(mod_mul((D_mod - 1 + MOD) % MOD, D_mod), INV2);
                ans = (ans + term2) % MOD;
                cur = m;
            }
        }
        cout << ans << '\n';
    }
    return 0;
}