
// Problem: A. Contest Start
// Contest: Codeforces - Codeforces Round #727 (Div. 2)
// URL: https://codeforces.com/contest/1539/problem/A
// Memory Limit: 256 MB
// Time Limit: 1000 ms
// Powered by CP Editor (https://github.com/cpeditor/cpeditor)

#include<bits/stdc++.h>
typedef long long int ll;
#define pb push_back
#define pi  3.141592653589793238462643383279
#define int long long
#define lld long double
#define ff first
#define ss second
#define endl '\n'
#define all(x) (x).begin(), (x).end()
#define rep(i,x,y) for(int i=(int)x; i<y; i++)
#define VI vector <int>
#define VVI vector <VI>
#define pii pair<int, int>
#define ppi pair<pii, int>
#define mii map<int, int>
#define mci map<char, int>
#define miv map<int, VI>
#define mis map<int, set<int>>
#define high_functioning_sociopath  ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
using namespace std;
const unsigned int M = 998244353;
/*_____________________________THE GAME IS ON_____________________________*/
void solve()
{
      int n,x,t;
      cin >> n >> x >> t;
      if(x>t)
      {
      	  cout << "0\n";
      	  return;
      }  
      int k = min(n-1,t/x);
      int res = (k*k + k)/2 + max(0ll,n-k-1)*k;
      cout << res << endl;
}
int32_t main()
{
   high_functioning_sociopath
   //pre();
   int t=1;
   cin>>t;
   while(t--)
   {
      solve();
   }
}