Thus is a multi-part party installment.
A famous host is storing his party recipes on a data server, and rumor has it that the passwords are in his house. He has another party today without his famous recipes, but it gives you a chance to steal the password. You and your friend start spying on the guests. Both of you need to go in as you need to bypass security, (part 2).
Guard: 1 Guest: 13 Guard: 3 Guest: 6 Guard: 125 Guest: 26 Guard: 31 Guest: 19
At this point your friend is spotted and is called on.
Guard: 9 Friend: 12
Surprisingly he gets in in. However, he still needs you to get the passwords. The entrance is about to close so you come out. Your number is 12, what should you reply?
Note: No codes or ciphers are used. Not dependent on day, or anything.
Convert to something computer-based
All guests have an electronic device with no calculator...
You pretend to go to the nearby restroom. You hear these responses:
Guard: 90 Guest: 24
Guard: 91 Guest: 25