import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
 
        // Read the number of test cases
        int t = sc.nextInt();
 
        for (int i = 0; i < t; i++) {
            // Read the number of friends
            long n = sc.nextLong();
 
            // Calculate the sum of numbers from 0 to n-1
            long sum = 0;
            for (long j = 0; j < n; j++) {
                sum += j;
            }
 
            // Output the sum
            System.out.println(sum);
        }
    }
}