#include<bits/stdc++.h>

using namespace std;

#define fast ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0)
#define ll long long
#define endl "\n"

void solve()
{
	ll n,x,t;

	cin>>n >>x>>t;

	ll temp = t/x;

	ll ans=0;
	if(temp>n)
	{
		ans = (n-1)*(n)/2;
	}  
	else
	{
		ans = n*temp;

		ans = ans - ((temp+1)*(temp)/2);
	}

	cout<<ans<<endl;

}

int main()
{
	fast;

	int t;
	cin>>t;
	
	while(t--)
	{
		solve();
	}
	
	return 0;
}
