#include<iostream>
#define ll long long int
#include<vector>
using namespace std;
int main(){
	ll tc; cin>>tc;
	while(tc--){
		ll n,x,t; cin>>n>>x>>t;
		ll z; 
		z=t/x;
		if(z>n) cout<<(n*(n-1))/2<<"\n";
		else {
			ll ans=z*n;
			ans-=((z+1)*z)/2;
			cout<<ans<<"\n";
			
		}
			
	}
}
