#include<bits/stdc++.h>

using namespace std;

#define PI 3.14159265
#define sqr(x) ((x)*(x))
#define pr pair<int, int>
#define vi vector<int>
#define vll vector<long long>
#define vull vector<unsigned long long>
#define all(v) ((v).begin()), ((v).end())
#define rev(v) ((v).rbegin()), ((v).rend())
#define rep(i, st, en) for(int i = st; i < en; i++)
#define Fast ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0)

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned long long int ulli;

ll gcd(ll a, ll b) { return b == 0 ? a : gcd(b, a % b); }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }


bool sortbysec(const pair<int,int> &a, const pair<int,int> &b) {
    return a.second < b.second;
}

template<typename T>
void takeInput(vector<T>& v){ for(auto& it : v) cin >> it; }

ll binPow(ll b, ll p) {
    if (p == 0) return 1;
    ll sq = binPow(b, p / 2);
    sq *= sq;

    if (p & 1)
        sq *= b;

    return sq;
}

int main() {
    Fast;

    int tc;
    cin >> tc;
    while(tc--){
        ll n, x, t;
        cin >> n >> x >> t;

        ll num = t / x;
        ll combin = (n - 1) - num + 1;
        if(combin <= 0 ){
            cout << n * (n - 1) / 2 << "\n";
            continue;
        }
        ll y = n - 1 - combin;
        y = y * (y + 1) / 2;
        combin = (combin) * num;
        cout << combin + y << "\n";
    }
    return 0;
}