#include<bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);
#define L 1000000007

int main(){
	fast
	int k;
	cin>>k;
	while(k--){
		long long n,x,t;
		cin>>n>>x>>t;
		long long val=t/x;
		long long ans;
		if(val>n){
			ans=n*(n-1)/2;
		}
		else{
			ans=val*(val-1)/2+abs((n-val))*val;
		}
		cout<<ans<<"\n"; 

	}
}
