#include <bits/stdc++.h>
using namespace std;
#define ll long long 
 
void solve(int test_case) 
{
        ll int n,x,t;
        cin>>n>>x>>t;
        if(t/x>=n)
        {
            cout<<n*(n-1)/2<<endl;
            return;
        }
        ll int m=x+t;
        ll int k=m/x-1;
        ll int sum=(k-1)*k/2;
        ll int c=(n-k)*k;
        ll int ans=c+sum;
        cout<<ans<<endl;
    }
 
int main()
{
    int tc=1;
    cin>>tc;
    while(tc--)
    {
        solve(tc);
    }
    return 0;
}