#include <iostream>
#include <vector>
#include <set> 
#include <algorithm>
#include<map>
#include <math.h>
using namespace std;
void solve(){
   int n,x,t;
   cin>>n>>x>>t;
   cout<<(long long)max(0,n-t/x)*(t/x) + (long long)min(n,t/x)*min(n-1,t/x-1)/2<<endl;
    
}

int main()
{
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int testCase;
    cin>>testCase;
    while (testCase--)
    {
        solve();
    }
    
}