#include <cstdio>
#include <cctype>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
template <typename T> inline void read(T &x) {
	T f = 1, ch = getchar(); x = 0;
	while (!isdigit(ch)) { f = ch == '-' ? -1 : 1, ch = getchar(); }
	while (isdigit(ch)) { x = x * 10 + ch - 48, ch = getchar(); }
	x *= f;
}
template <typename T> void print(T x){
	if (x < 0) { putchar('-'); print(-x); }
	if (x > 9) { print( x / 10); }
	putchar(x % 10 + '0');
}
template <typename T,typename... Args> inline void read(T &t,Args&... args) {
	read(t);read(args...);
}

long long T, n, x, t;
int main() {
    read(T);
    while (T--) {
        read(n, x, t);
        long long mid = t / x;
        if (n < mid) {
            print((n - 1) * n / 2);
        }
        else {
            print((n - mid) * mid + (mid - 1) * mid / 2);
        }
        puts("");
    }
    return 0;
}