#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define FAST1 ios_base::sync_with_stdio(false);
#define FAST2 cin.tie(NULL);
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define FAST1 ios_base::sync_with_stdio(false);
#define FAST2 cin.tie(NULL);
 
 
void solve(){
    ll n,x,t;
    cin>>n>>x>>t;
    ll val=min(n-1,t/x);
    if(val==0){
        cout<<0<<endl;
        return;
    }
    ll summ=max(0ll,val*(val-1)/2)+val*(n-val);
    cout<<summ<<endl;
}
 
int main(){
    FAST1;
    FAST2;
    ll t;
    cin>>t;
    while(t--){
        solve();
    }
}