Write a program which triples (*3) every third element, starting with 0, in the existing array named array.

Below program will do the needful task. There might be some other ways to do so as well. 
 
package day12Project;
public class Main {
public static void main(String[] args) {
 int[] arr = {1000,2,3,4,5,6,7,8,900,34,353,24,534,245,345,342,5435,343,53,423,24,353};
 for (int i = 2; i < arr.length; i = i+3) {
  System.out.println(arr[i]*3);
 }
}
}