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

int main()
{
	int k;  cin >> k;
	while(k--)
	{
		ll final = 0, n, x, t;
		cin >> n >> x >> t;
		ll ans = min((n-1), t/x);
		final = final + (1 + ans)*ans /2;
		final = final + (n-ans-1)*ans;
		cout << final << endl;
	} 
	return 0;
} 
