#include<bits/stdc++.h>
#define rep(X,A,B) for(int X=A;X<=B;X++)
#define tep(X,A,B) for(int X=A;X>=B;X--)
#define LL long long
const LL INF=1e9+7;
const int MX=25;
const int N=100010;
const int M=N<<1;
using namespace std;

void SOLVE(){
	LL n,x,t;
	scanf("%lld%lld%lld",&n,&x,&t);
	LL now=t/x;
	if(n-1<=now){
		printf("%lld\n",(n-1)*n/2);
	} 
	else{
		LL ans=(now-1)*now/2;
		ans+=(n-now)*now;
		printf("%lld\n",ans);
	}
}

int main(){
	int T;
	scanf("%d",&T);
	while(T--)SOLVE();
	return 0;
}
