Unknown knowable things of the mind blowing variety.
September 6, 2013 2:24 PM   Subscribe

Yesterday, while walking to the store with my mom, she absolutely blew my mind when she pointed out to me that the model year of almost every car is embedded somewhere in a semi-standard code in the plastic on the tail light, or headlight, assembly. This raises two questions...

First, what more can anyone tell me about this tail light code in contemporary cars? Is there standard number coding for other data points aside from country of assembly and model year? These codes all have something like SAE USA 02 DOT in there somewhere, but different makes (because yes of course I then checked all the cars on the block) have these elements in different orders. What other things can these codes tell me?
Second, and more importantly and generally, what other data points like this are just hiding in plain sight... related to anything, not just cars. I want to know more things like this little model year trick. So, clever mefites, out do my mom: tell me the cryptic facts that are 99% invisible to most people most of the time.
posted by Cold Lurkey to Grab Bag (31 answers total) 112 users marked this as a favorite
If you pull the seatbelt out from the reel, there's a label with the model year. (At least that's what Mike on Wheeler Dealers says).
posted by The Deej at 2:28 PM on September 6, 2013

As you board an airplane, look for a metal plaque inside the door frame or on the exposed edge of the door, to the left- it'll have the plane's model year on it.
posted by moonmilk at 2:28 PM on September 6, 2013

Two things:

Pennies are stamped where they were minted: Pennies minted in Denver have a D stamped below the year, pennies minted in Philadelphia have no stamp.

Silver jewelry is stamped with its percentage of silver content. Check near the clasp: Chains stamped with 925 are 92.5% silver. There are reports of false stamping though.
posted by chainsofreedom at 2:33 PM on September 6, 2013

Best answer: The first 4 digits of your drivers license number, if it begins with a letter, is usually a Soundex code which yields your last name. https://en.wikipedia.org/wiki/Soundex
posted by brownrd at 2:52 PM on September 6, 2013 [12 favorites]

I assume you literally mean the ones on the taillight or headlight assembly and not other stuff like the VIN?
posted by tel3path at 2:52 PM on September 6, 2013

All US coins (not just pennies) get a mint mark. D's Denver, P's Philly, S is San Francisco and W is West Point, though the latter two typically don't circulate. Pennies without a mark are ostensibly produced in Philadelphia, but Wikipedia says sometimes San Francisco and West Point also produce pennies (the missing mark is so that there aren't scarce varieties).
posted by brentajones at 2:54 PM on September 6, 2013 [1 favorite]

Costco doesn't go out of its way to indicate which of its wares are marked down, but apparently there are small tells on the tags. This guy spent way too much effort deciphering their "secret price codes."
posted by Iridic at 2:56 PM on September 6, 2013 [8 favorites]

Brentajones: how interesting!

I also remembered something else - Social Security numbers are based on your zip code. I found this out at a conference where we were placed into groups via SSN. Everyone in my group was from either my state or one of the adjacent ones!
posted by chainsofreedom at 2:57 PM on September 6, 2013

On the gas gauge in a car, there is an arrow as part of fuel pump symbol. It's pointing to the side of the car that has the tank.
posted by the jam at 3:21 PM on September 6, 2013 [16 favorites]

In my county, a criminal defendant's 8-digit case number contains several pieces of information (even most criminal defense attorneys don't know this). From that number, you can tell the year the charge was filed, whether a person was physically arrested or given a citation, whether the person is a man or a woman (because one digit signifies whether the defendant was booked into the men or women's jail), and whether they were taken to the hospital. There may be more info in there that I'm forgetting.
posted by Unified Theory at 3:33 PM on September 6, 2013

Best answer: The lights on the front of a CTA train indicate which line it is. (I looked but didn't find a current list. No love for the pink line.)
posted by hydrophonic at 3:51 PM on September 6, 2013 [1 favorite]

Note: Social Security Numbers predate zip codes, but they are obviously somehow tied to location.
posted by she's not there at 4:10 PM on September 6, 2013

In Illinois your birth year is in your driver's license number, e.g., B111-1115-4111 indicates the birth year 1954.

I learned this while trying to by beer ~1972 when I was driving on a ticket for a moving violation. The arresting officer had incorrectly entered "1951" as my birth year. Unfortunately, he had correctly transcribed my license number.
posted by she's not there at 4:19 PM on September 6, 2013

Zip codes go from lowest (Agawam MA, though nitpickers might disagree) to highest (Ketchikan AK) in a roughly east to west order. Here's a map. A lot of numbers things have contain systems of numbers within them.
- ISBNs on books similarly tell you the publisher and a few other details. Here's a diagram (details).
- UPC codes break down into similar ways but there is sort of a decision tree based on the earlier numbers as to what the later numbers mean.
- Credit card numbers also break down with some information hidden in them.
posted by jessamyn at 4:37 PM on September 6, 2013 [1 favorite]

There should be a label on the door frame of the driver's side of your car telling you what the correct tyre pressure should be for both front and back tyres.
posted by essexjan at 5:18 PM on September 6, 2013 [1 favorite]

In Illinois, your name and birthday are also encoded in the date. Try it here.

Credit cards always start with the number of the system:

4 = Visa
5 = Mastercard
6 = Discover
7 = Amex

Target puts a '4' in the cents position on items that are on final clearance. They won't be marked down any more.

Back when McDonalds made burgers ahead of time and they sat in that warming tray, there were little cards stuck between the burgers with numbers on them. The number signified the time 10 minutes after they were made (e.g. burgers made at 10:15 = "3" on the big hand, so the '5' card would be put by those burgers and thrown in the trash at 10:25). You could tell what was fresh and what was stale.
posted by JoeZydeco at 6:42 PM on September 6, 2013 [1 favorite]

JoeZydeco, that Illinois drivers license decoder has utterly blown my mind! Thanks. One slight correction, AMEX cards all start with at 3, not a 7. This I learned as a cashier at a B. Dalton bookstore in the late 1980s, and I still trot it out today.
posted by JimInLoganSquare at 6:58 PM on September 6, 2013 [1 favorite]

Oops yeah you're right, JimInLoganSquare. Sorry folks.
posted by JoeZydeco at 7:15 PM on September 6, 2013

The first three digits of Social Security numbers have typically been tied to the state of the office that issued the number (numbers issued prior to 1973) or the state of mailing address of the recipient (number issued from 1973 to 2011). Since 2011, the first three digits of any new numbers are random. (List of prefixes and associated states)

I haven't been able to confirm, but it's my understanding that Social Security switched to random numbers since they were running out of numbers associated with some faster-growing states.
posted by potential lunch winner at 7:19 PM on September 6, 2013

My mind was also blown when I gave my doctor (or similar) my SSN and he said, "Oh, born in New York, huh?"

The easiest info to discern from an ISBN / back of a book is that the last four digits above the right-hand barcode are often the retail price (like ...2499 = $24.99). I cannot tell you how many times I tell this to customers, being a bookslinger by trade.
posted by wintersonata9 at 7:41 PM on September 6, 2013 [2 favorites]

It's hard to tell what's surprising and what's common knowledge. (WTF PINEAPPLES!) But, here are a few random similar things that have surprised either me or other people:

- There are lots of examples of Morse code embedded in the world without context. For example, at least until recently many Nokia cell phones used "SMS" as their default text message ringtone. Trilogy brand keypad door locks send "73" (which is ham radio shorthand for "goodbye") when exiting programming mode. Many old newsreels and modern simulations generally repeat "NEWS" over and over again as the background sound in the beginning of the films. The blinking light on the Capital records building in Hollywood, CA flashes "hollywood" very slowly. Western Digital external hard drive enclosures often have coded air vents. In general, it's pretty rare to hear or see something that sounds like Morse code in popular culture that isn't actually meaningful.

- In the US at least, a blue colored road reflector (cat's eye) indicates the location of fire-hydrants or equivalent hookups.

- The colors used in bundled multi-conductor cables are usually drawn from one single set of colored pairs which are historically map to numbers. The world is full of people who don't know this, so you can't assume the numbered pairs correspond to the numbered pins on a connector. But, if you're using professionally made cables there's a good chance they'll be correct. (And, if you use it when making cables, it saves you having to carry around a project-specific lookup table.)

- The first six hex digits of a wireless device's mac address are drawn from lists registered to specific companies. If you know someone's real mac address, you also know who made their computer/network-card/router.

- These may not count, since it's obvious that *something* is being encoded, but surveyor's paint colors and hazard diamonds are both readily decoded.
posted by eotvos at 8:06 PM on September 6, 2013 [3 favorites]

The first two digits in a street address in Vancouver, Canada tell you the cross avenue, if you subtract 16. So 2800 Granville St is at 12th and Granville. 3200 Oak is at 16th.
posted by Chaussette and the Pussy Cats at 8:12 PM on September 6, 2013 [5 favorites]

U.S. Interstate numbers have a system. Odd numbers run north/south. Smaller numbers start in the west. Even numbered interstates run (roughly) east to west, with smaller numbers in the south.

Three-digit interstates that start with an even number will eventually meet back up with the interstate they deviated from. Three-digit interstates that start with an odd number will not hook back up with the original interstate. (I thought that there was something about 2XX going around a city, and 4xxx going through a city, but I can't find evidence to back that up.)

Most on this all here.
posted by hydra77 at 10:50 PM on September 6, 2013 [2 favorites]

Many cars have a little triangle on one side or the other of the gas pump symbol for the gas gauge. It's an arrow pointing to the side of the car with the gas tank.
posted by nat at 11:51 PM on September 6, 2013

Because Washington DC is organized into quadrants, it's important to know the compass points to orientate yourself. At the base of all the streetlamps is a compass rose indicating which direction is north. Very handy!
posted by orrnyereg at 12:56 AM on September 7, 2013 [8 favorites]

Malaysian ID cards encode your birthdate, your place of birth, and your gender.


First 6 digits - YY, MM, DD
Middle 2 digits - state of birth; 01 is Johor, etc. 71 means you were born outside Malaysia.
Last 4 digits - random, but if it's an even number as the last digit the person's female; if odd, male
posted by divabat at 3:41 PM on September 7, 2013 [2 favorites]

potential lunch winner: "(List of prefixes and associated states)"

This chart says "Not issued" for the first 3 digits of my SSN. What does that even mean?
posted by secretseasons at 4:23 PM on September 7, 2013

It's no longer as meaningful with all the newer area codes that have been created, but under the original US telephone area code system (where the middle digit was always a 0 or a 1), you could tell how major a location was based on how far you had to spin a rotary dial to call that area code. So 212 went to New York City, Los Angeles got 213 and Chicago 312, and areas with lower population had a 0 in the middle instead of a 1.
posted by jessypie at 4:28 PM on September 7, 2013 [4 favorites]

Best answer: Not that surprising, but those spray-painted lines on the street or more often near the curb?

They represent the utility line that is running underneath the area spray-painted. Used to mark them by contractors to
Yellow: natural gas
blue: water
green: sewer line (dirty water)
white: where they're proposing to dig out the ground
orange: internet/cable TV
red: electricity

One you begin to notice them, you'll see them everywhere.
posted by fizzix at 9:27 AM on September 10, 2013 [3 favorites]

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