/*              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!!               */