#include <bits/stdc++.h>
using namespace std;
typedef long long i64; 

int n, c; 
i64 solve1(void) {
    i64 x = min(n / c, (c + 1) / 2); 
    return 1ll * n * (n + 1) / 2 + 1ll * c * (c - 1) / 2 * x - 1ll * x * (x - 1) / 2 * c;
}
i64 solve2(void) {
    i64 x = n / (c + 1) + 1; 
    return 1ll * x * n * c - 1ll * x * (x - 1) / 2 * c * (c + 1); 
}
void solve(void) {
    cin >> n >> c; 
    int ans = max(solve1(), solve2());
    cout << ans << "\n"; 
}
int main(void) {
    ios::sync_with_stdio(0); 
    int T; cin >> T; 
    while (T--) solve(); 
    return 0;
}