#include<bits/stdc++.h>
using namespace std;
#define ll   long long int
#define vl vector<long long int>
#define fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define all(x) x.begin(),x.end()
#define vi vector<int>
#define vb vector<bool>
#define vvl vector<vector<ll> >
#define vvi vector<vector<int> >
#define pll pair<ll,ll>
#define pb push_back
#define PI 3.14159265
#define mp make_pair
#define fri(s,n) for(ll i=s;i<n;i++)
#define frj(s,n) for(ll j=s;j<n;j++)
#define t(i) ll i=1;cin>>i;while(i--)
#define vsl vector<set<ll> >
#define pll pair<ll,ll>
#define vpii vector<pair<int,int> >
#define mod 1000000007

/*#include<ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>,rb_tree_tag,tree_order_statistics_node_update> pbds;
*/
void solve(){
	ll n,x,time;
	cin>>n>>x>>time;
	ll z=time/x;
	ll p=max(0ll,n-z);
	ll ans=p*z;
	z=min(n,z);
	ans+=(z*(z-1))/2;
	cout<<ans<<'\n';
	
	

}
int main()
{ios_base::sync_with_stdio(false);cin.tie(0);cin.tie(0);
	//freopen("pails.in", "r", stdin);
  //freopen("pails.out", "w", stdout);
	 int t=1;
	 cin>>t;
	 while(t--)solve();
	 
return 0;}
