A salty puzzle

When last we left our intrepid post-Apocalyptic explorer, he was deep in the middle of Fish Week (aka Freshman Orientation) at the local U. We decided to check out a large crate:

Aha! NaCl, what could that possibly mean ... apparently it's the kind of thing you don't have to know, you just have to be perceptive enough to figure it out. Somehow. Luckily we roll a 6 on the Idiot-O-Meter, clearing us to:

Hey, it's salt, everybody! Who knew that NaCl was salt?! Well, we can certainly see the value of a college education, that's for darn sure. I bet behind the door is shelf after shelf of tequila and margarita glasses! Our choice at this point is to either head back to the caravan with our ill-gotten goods, or move on to checking out the door. Given the tenor of our last debate (aka "Pillage Everything"), I'm going to skip ahead and decide to check out the door:

Oooo, a puzzle! How exciting! Given this universe's amazing ability to intuit scientific information just by looking around, hopefully the answer will just come to us, BAM. I'll wait.


OK, not so much. Dang. Looks like we'll have to figure this one out ourselves. Take a crack at it and leave your best guess with your reasoning in the comments. Maybe when we get enough that seem reasonable we'll put it up to a vote. Put on those Santa-shaped thinking caps, folks!

17 Responses to A salty puzzle

  1. borntobealoser says:

    Right, I’ve literally only looked at the puzzle for a few seconds, and I’m shouting the first thought that came into my head. Forgive me if I’m wrong, but don’t you get the last number of each row if you add the first 2 numbers of each row and take away the third number in the row?

    Like this:
    2 + 12 = 14, 14 – 5 = 9.
    4 + 20 = 24, 24 – 7 = 17.

    So, going on that, surely it’s:
    12 + 12 = 24, 24 – 4 = 20.

    If that’s wrong, I’m going to look like a total idiot…

  2. Worf says:

    I think borntobealoser is correct. I came to the same conclusion.

    So unless someone has a better idea, 20 seems to be the answer.

  3. MartianBlue says:

    I arrived at 20 by different means than these two, but still came up with 20 none the less.

    first row +2 +8 +2 +8 equals second row and second row +8 -8 -3 +3 equals third row so secret number =20

  4. Tarkabarka says:

    I agree with borntobealoser, i also have this idea. So the answer is 20

  5. Dan says:

    Is anyone else sitting here with the Butthead face on? I’m gonna leave this one to you guys who are good with the numbers.

  6. Brad says:

    Dan, you aren’t alone. I honestly jumped to the comments just hoping someone had worked it out.

  7. Gero says:

    I’m casting my vote for born’s 20. Seems like sound reasoning to me…

  8. Myro says:

    Oh good. I’m not the only one that looked at this and said, “Duh?”

    I’m sure if I had more sleep, I’d have been able to work this one out, but for those that have worked it out, I have to agree with the results. I’m willing to go with 20 as well.

  9. Jeff Hebert says:

    Damn, borntobealoser, that’s some fast and impressive work! I don’t know if it’s right or not as I haven’t looked it up to see, but it’s certainly a persuasive case. Can anyone come up with an alternative that also makes sense but comes to a different answer?

    I’ll freely join the “Math idiot” club here as I didn’t see a solution at all.

  10. Let’s see…

    12 shots of Jaegermeister + 12 beers at the start of a 4 day weekend… -$2000 over Xmas.

  11. William A. Peterson says:

    I’m awful with puzzles, but the “20” answer looks correct. On the other hand, I knew that NaCl was salt without having to look anything up! Of course, I’d bring the Salt back to the convoy, and THEN went back to the steel door, with about 20 friends armed to the teeth, just in case…
    But, I’m guessing that wasn’t an option.

  12. spidercow2010 says:

    20 sounds good, but hey, MartianBlue, how’d you arrive at that final +3? Wait, I just noticed: the two columns on the left add up to the same thing as the two columns on the right, so the last two numbers have to add up to 12+12. Yeah, it’s gotta be 20.
    I really wonder what’s on pg.171.

  13. Worf says:

    I think MartianBlue somehow got lucky. If what borntobealoser and I thought out is correct, then just about any other combination of numbers that use that method won’t work with MB’s method. I will, however, be the first to congratulate him if his method is the correct one.

  14. Dan says:

    @spidercow, I’d wager that pg. 171 involves an explosion and our face.

  15. Gero says:

    @spider12/worf13: He got the +3 from the pattern he noticed. The first half of the last row had 8’s (one adding 8, one subtracting 8), so he knew the second half would also have the same number, used both in addition and subtraction. Since we already have the number you’d get from subtracting 3, he knew to get the final, missing number you just have to add 3 to 17 and BAM 20…

  16. spidercow2010 says:

    I follow that, but it seems awfully like the pattern is being arrived at thru deciding what the unknown number is rather than vice versa. Maybe I’m missing something; it wouldn’t be the first time. And it doesn’t matter anyway: a), postulating an answer and testing it against obsrved phenomena is the scientific method and b) it works, so what am I complaining about?

  17. Gero says:

    You don’t need to know the 20 first to do martian’s. He just found a separate pattern that also worked. Rather than adding left to right, he did up and down. That’s the only difference between the two methods…