The Security to the Party [Part 30] [#1]

Question

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.

Hint: Morse code cryptogram now solved!
Hint: Vigenere text cipher now solved!

Convert to something computer-based
All guests have an electronic device with no calculator...

Bonus Guests:

You pretend to go to the nearby restroom. You hear these responses:
Guard: 90 Guest: 24
Guard: 91 Guest: 25

Answer 1

The answer is...

18

Explanation...

If you convert the ASCII character to its decimal value and add the digits

1 => 49 => 4+9=13
3 => 51 => 5+1=6
90 => 57, 48 => 5+7+4+8=24
91 => 57, 49 => 5+7+4+9=25
12 => 49, 50 => 4+9+5+0=18

Answer 2

The binary conversion of the two number, the one asked by the guard and the one answered by the guests, has the same parity alas the same number of 1 (e.g. 3 is 11 and 6 is 110, 125 is 1111101 and 24 is 11000). My logic is really simple, yet I had to try since you referred to computers in the morse code cryptogram :)

Answer 3

Old answer:

You have got the following questions and answers: Guard: 1 Guest: 13
Guard: 3 Guest: 6
Guard: 9 Guest: 12
Guard: 31 Guest: 19
Guard: 90 Guest: 24
Guard: 91 Guest: 25
Guard: 125 Guest: 19
If you want to know the answer of the guard when he is saying: 31. You are combining the 3 and the 1 question together and sum them up. So question 3 + 1 = 13 + 6 = 19. to answer the question of 91 you combine 9 and 1 which are 12 + 13 = 25. We need to answer the question "12" so we need the digits "1" and "2". We know 1 which is 13 so we only need 2. We dont know 2 but we can calculate it by looking at the question 125. 125 contains the digits "1", "2" and "5". We know 1 which is 13 and 19 - 13 = 6. I almost know the answer but need to think a >!little bit more about it.

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Update!

New answer:

Now Quynguyen gave us the hints I tried and combine the answers of the 2 other puzzles. I used a vigenere cipher and entered the folowing: Plain: Quynguyen Key: Computers output was: nflxlatmu some letters of the alphabet are reflecting with the numbers like f is the sixth letter so the answer was six. I think I'm close. I hope someone solves this because I want the answer to this puzzle!

Answer 4

I think the answer is

18

Edit- okay, someone else posted while I was trying to log in. I had the right answer but was using a completely different method that was ultimately not consistent. Oh well.

Edit 2-

I found the digital root of the original number (ie, added all the digits) and compared them with the answers. I noted that two numbers both were 9 (9 and 90) and that their answers were 12 and 24. The difference between the two is the number of initial digits present, and noting that the difference between the answers is 12, I applied the same logic to the other initial answer that had 3 (which is the same as sum of the digits of the 12 that needs a response), added 12 to the 6 that was the answer to 3, and got 18. This doesn't explain anything else in the problem though, it's a complete coincidence that I got the right answer.