// Reverse Diagonal
for (int i = 0; i < space; i++){
    System.out.print(num + " ");
    num++;

    for(int j = 0; j < space; j++){
      if (j + i == 5) {
        System.out.print(" *");
      }
      else {
        System.out.print(" ");
      }
    }
    System.out.println();
}