Sorry I don't get it. How the winner will be pick ?
A coded "hat" that will generate a random number. And if you order 7 tickets, your number will be from 1-7. And if another person orders 4, their number will be 8-11. So the number will be between 1-11. If it is from 1-7, it goes to you, if it is from 8-11, it goes to the other person.
Why not just use Random.org and do it over join.me to make it 100% fair and no cheating.