#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll mod=1e9+7;
#define pb push_back
#define re(i,n) for(ll i=0;i<n;i++)
#define reb(i,n) for(ll i=n;i>0;i--)
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<string> vs;
typedef map<ll,int> ml;
typedef map<char,ll> mc;
typedef map<string,ll> ms;
typedef vector<pair<ll,ll>> vpl;




int main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);

   #ifndef ONLINE_JUDGE
   freopen("input.txt","r",stdin);
   freopen("output.txt","w",stdout);
   #endif
 int t; cin>>t;
 while(t--){
 ll n,x,t; cin>>n>>x>>t; ll dis=t/x;
 (dis > n)?cout<<(n*(n-1))/2<<'\n': cout<<n*dis-(dis*(dis+1))/2<<'\n';
}
   return 0;
 }
