How to Decode Credit Card Numbers

Video written by Adam Chase

[TheRealGuywithoutaMustache]

2:46 You gotta feel sorry for Scarn McDunweather, someone who's seen this video had to have stolen his credit card number by now

[JoePug]

I work for a company that sells flags and flagpoles, so I take credit card numbers over the phone basically every day. It's always a cool party trick when they start out with "It's a Discover, " or "It's a Chase debit card, " and I just start saying the first four numbers for them. Amazes them every time lol

[bobafettjr]

I love how your example card starts with a 4 but has a "mastercard" logo. Mastercard always start with 5 and Visa 4.

[HipyoTech]

I tried this on people and got a call from the FBI asking about bricks.

[greenor]

"Show me your credit card number so I can guess your zodiac sign"

[luuketaylor]

This finally answers the question I've had for a long time about how online payment portals knew which card I had after just typing in the first 4 digits. Thanks, Sam from HAI.

[vladyslavpidlisnyi]

What an interesting video about bricks! Never thought about them in this way.

[mithramusic]

One thing i wish you'd mention when you bring up the concept of not using every available possible number "because then online shopping becomes a game of making up a number and hoping it doesn't belong to your friend" is the fact that you need to authorize transactions with the right expiration date and CVV code, and often even your zip code or billing address

[theyetirulrs]

I swear this channel has the highest volume of truly useless useful knowledge! Love it!

[krankolojigd]

Some banks started issuing 19 digit cards. In fact, to be certified by Mastercard, you need to be able to process 19 digit cards.

Also, the card number in the thumbnail fails the luhn algorithm check.

[zylianari]

This one was literally taught to us in one of my college classes, and the funny thing is, I'm a medical student. To this day I still wonder where can I actually use this.

[Ozymoron]

Sam, I've noticed a terrible blunder in your video. At 0:30 when you show the credit card, the credit card number starts with a 4 but the card shows a MasterCard logo in the bottom right. If a credit card starts with 4 it will be a VISA card, MasterCard starts with 5.

[SantaBunny]

Calling our parties a bunch of nerds sitting in a room is hurtful…. True…. But hurtful

[moski]

This is actually something I’ve wondered about for years but thought I’d end up on a list for looking up.. well done!

[QVW]

*He really just called all of us nerds.*

[allanrichardson]

On running out of numbers: the 9 digit individual account number only has to be unique WITHIN a specific value of the first six digits. Each issuing bank has one OR MORE six digit prefixes (Chase and Wells Fargo probably have dozens of prefixes; a medium size community bank would have one; and a number of really tiny issuers would divide a prefix among themselves). So the number of possible accounts is not limited to 10^9 in the world, only 10^9 within a single issuer prefix.

[jdatlas]

I… um… know that system. Am I really that kind of nerd? I’d ask someone else but they all left hours ago when I started going on about encoding schemes and checksums.

[stevegruber]

to be fair, my parties are a bunch of nerds sitting in a room, well, some nerds, okay, a couple nerds, okay, just me

[cheezfri]

"The next 5-7 digits represent the credit network, like Visa or Mastercard." No, not really. The first digit already does that. 4 is Visa and 5 (and more recently 2) is Mastercard. The first 6 digits (and now 8 for some cards) is known as the BIN. Sorry I forget what that stands for, but primarily the issuing banks like Chase and BOA are assigned BINs, which they can use for various reasons such as identifying what sort of account you have (gold, platinum, World, etc.) And this isn't even 100% true, as some banks let you switch products but keep your old card number. There is a sophisticated system that keeps track of that. I'm a former Mastercard employee and dealt with that all the time.

[lucacyrus]

Yes, I will know go to senior parties and show them this to fit in as a freshman and black mail them