/*              Jai Maa Saraswati!!           */
#include<bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<string.h>
#include<math.h>
#define IOS ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define ll long long 
#define pb push_back
#define mod 1000000007
#define F first
#define S second
#define mp make_pair
#define vi vector<int>
#define vll vector<long long>
#define all(x) x.begin(),x.end()
#define dbg(x) cout<<" "<< #x << "=" << x <<" "; //for debugging
 
using namespace std;
bool isprime(ll n)
{
    //if(n<2)
    //return false;
    if(n==1)
    return true;
    if(n==2 || n==3)
    return true;
    if(n%2==0)return false;
    for(ll i=3;i*i<=n;i+=2)
    {
        if(n%i==0)
        return false;
        
    }
    return true;
}
bool checkpalindrome(ll c)
{ 
    string p=to_string(c); 
       int j = p.size() - 1;
 
    for (int i = 0; i < j; i++, j--)
    {
        if (p[i] != p[j])
        {
            return false;
        }
    }
 
    return true;
}
ll gcd(ll a,ll b)
{
    if(a==0)
    return b;
    return gcd(b%a,a);
}
ll lcm(ll a,ll b)
{
    return a*(b/gcd(a,b));
}
 set<ll> fac;
void allFactors(ll n)
{
   // set<ll> fac;
    for(ll i=1;i<=sqrt(n);i++)
    {
        if(n%i==0)
        {
            fac.insert(i);
            if(i!=n/i)
            {
                fac.insert(n/i);
            }
        }
    }
    //return fac.size();
}
bool threefactors(ll n)//when you have need of a no which is divisible by 1,itself,any other one no.
{
    ll p=sqrt(n);
    if(p*p==n)
    {
        if(isprime(p))
        return 1;
        else
        return 0;
    }
    else
    return 0;
}
unsigned int countSetBits(unsigned int n) //no. of 1's in a binary representation of a number
{ 
    unsigned int count = 0; 
    while (n) { 
        count += n & 1; 
        n >>= 1; 
    } 
    return count; 
} 
int computeXOR(int n)
{
  if(n%4==0)
  return n;                        //TO CALCULATE XOR FROM 1 TO N
  if(n%4==1)
  return 1;
  if(n%4==2)
  return n+1;
  else
  return 0;
}
ll largest_power(ll N)
    {                                              //LARGEST POWER OF 2 JUST LESS THAN OR EQUAL TO A GIVEN 16 BIT NUMBER
        //changing all right side bits to 1.
        N = N| (N>>1);
        N = N| (N>>2);
        N = N| (N>>4);
        N = N| (N>>8);
        N = N| (N>>16);  
 
    //as now the number is 2 * x-1, where x is required answer, so adding 1 and dividing it by
                return (N+1)>>1;
 
    }
ll fibo(ll n)
{
    long double him=(1+sqrt(5))/2;
  return round(pow(him,n)/sqrt(5));
} 
//pair(weight,pair(u,v));
void kruskal(vector<pair<ll,pair<int,int>>> v)
{
     sort(v.begin(),v.end());
    set<int> s;
    ll ans=0;
    for(int i=0;i<v.size() && s.size()<8;i++)
    {
        if(s.count(v[i].S.F) && s.count(v[i].S.S))
        {
            
        }
        else
        {
            ans+=v[i].F;
            s.insert(v[i].S.F);
            s.insert(v[i].S.S);
        }
    }
    cout<<ans;
}
/*                      Jai Shree Krishna!!
                        Jai Shree Ram!!
                     Jai Shiv Shambhu Sai Ram!!                      */  

void solve()
{
    ll n,x,t;
    cin>>n>>x>>t;
    ll a=0,b=1,cnt;
     a=t/x;
     if(a<=n)
     {
     cnt=a*(n-1);
     a--;
     cnt-=(a*(a+1))/2;
     }
     else
     {
         n--;
         cnt=(n*(n+1))/2;
     }
     cout<<max(0LL,cnt)<<endl;
    
    
    
}
int main()
{
     #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
     #endif
     IOS
     int test_cases=1; 
     cin>>test_cases;
     while(test_cases--)
     {
         solve();
     }
     return 0;
} 
//ascii of a=97
//ascii of A=65
//ascii of 0=48
// priority_queue<ll,vector<ll>,greater<ll>>pq; ascending queue
//lower_bound and upper_bound
/*   for erasing in vector
    1.you MUST declare a vector with its size or fill values using push_back
    2.v[]={0,1,2,3,4,5,6};
    3.v.erase(v.begin()+2);=>0 1 3 4 5 6
    4.Again v[]={0,1,2,3,4,5,6};
    5.v.erase(v.begin()+2,v.begin()+4);=>0 1 4 5 6
*/
/*              Har Har Mahadev!!               */