#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define vi vector<long long int>
#define pb push_back
void solve(void);
int main(){
{int t;
cin>>t;
while(t--)
	{solve();}

}
return 0;
}
void solve(){
ll n,x,t,m;
cin>>n>>x>>t;
m=t/x;
if(n==1)
    {cout<<"0"<<endl;
    return;}
//cout<<n-1<<" "<<m<<endl;
if(n-1<=m)
{ll e=n-1;

cout<<(e*(e+1))/2<<endl;
}
else
{ll u=n-m;
ll ans=u*m;
ans+=((m)*(m-1))/2;
cout<<ans<<endl;

}
}
