#include<bits/stdc++.h>
using namespace std;

#define int long long

int T, n, x, t; 

signed main(){
	cin >> T;
	while(T --){
		scanf("%lld%lld%lld", &n, &x, &t);
		if(x > t)
			puts("0");
		else{
			int tmp = min(t / x, n - 1);
			int ans = tmp * (n - tmp - 1) + (tmp + 1) * tmp / 2;
			cout << ans << "\n"; 
		}
	}
	return 0;
} 