#include<bits/stdc++.h>
#include <string>
using namespace std;
#define ll long long int
//for(const auto& x : m)

int main ()
{

    ll test;
    cin>>test;
    while(test--)
    {
        ll n,x,t;
        cin>>n>>x>>t;
        ll a=t/x;
        if(a>=n)
        {
            a=n-1;
        }
        ll ans=(a*(a+1))/2;
        ll d=n-a-1;
        ll p=ans+(d*a);
        cout<<p<<endl;
    }


    return 0;
}
