#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;
typedef vector<ll> vl;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
typedef vector<pii> vpii;




void solve(){

    ll n,x,t;
    cin>>n>>x>>t;
    ll k = t/x;
    if(k>n){
        cout<< (n*(n-1))/2<<"\n";
        return;
    }
    ll dis = n*k;
    dis-=((k)*(k+1))/2;
    
    cout<<dis<<"\n";
}




int main(){
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);

    #ifndef ONLINE_JUDGE
        freopen("input.txt","r",stdin);
        freopen("output.txt","w",stdout);
    
    #endif // !ONLINE_JUDGE
    
    int T;
    cin>>T;
    
    while(T--)
        solve();
    return 0;
}