#include <iostream>
#define ll long long int

int main(void)
{
    ll t = 0;
    std::cin >> t;
    while ( t --)
    {
        ll n , x , t;
        n = x = t = 0;
        std::cin >> n >> x >> t;
        ll tx = t / x;

        if (x > t)
        {
            std::cout << 0 << "\n";
        }
        else if (tx >= n - 1)
        {
            std::cout << (n * (n - 1)) / 2 << "\n";
        }
        else
        {
            ll full_start_at = (n - (n - tx)) + 1;
            ll res = (full_start_at * (full_start_at - 1)) / 2;
            
            std::cout << res + ((n - full_start_at) * tx) << "\n";
        }
    }
    return 0;
}