The Very-Many-Questions-Not-Worth-Their-Own-Thread Thread XXXVIII

[cardgame]

The initial 4 digits, iirc, specify exactly which type of card it is - visa, mastercard, discover, etc.

The rest is over my head

 

[Kyriakos]

Just had a look at the wiki entry, and not sure if Tim is thinking of the right algorithm there, or Kyriakos of the right purpose.
The purpose seems to be to check for accidental mistyping of credit card numbers, which leads to only one digit being automatically created.
And the reason why it's used is probably because it's simple. You can easily implement it, is fast to execute, implementations are available, and it reasonably well protects against most errors.
You probably would not gain much with a more complicated algorithm.

Well, all credit card numbers use the luhn algorithm, though obviously not all numbers that do are real credit card ones
But yes, given the system has other ways of checking if the number is indeed a credit card, it does seem a bit redundant. Maybe at some past it was the core security measure for online checking (at least in the early internet, checking was done in stages, with the system taking some time to connect to a bank/do whatever to verify), but now is just one of many? Or, alternatively, maybe it started not as a safety measure but a way for the bank to generate the next free number more easily, but without having a more obvious/blatant sequence like for example simply adding +1 (?).

(as always, I just need this for a story - honest )

 

[rah]

Actually in the old days it was prior to on-line checking and this was the first defense against fraud. (and data entry error)
Most people were not even aware it existed. You would be amazed at how many people were caught with this basic check.

 

[Kyriakos]

Actually in the old days it was prior to on-line checking and this was the first defense against fraud. (and data entry error)
Most people were not even aware it existed. You would be amazed at how many people were caught with this basic check.

It just seems a bit strange an algorithm to choose, if it started before wide-spread computer checking. Cause in that case you don't need to code the search engine for it and something faster for a human could have been better, eg the very fast search for whether a number is perfectly divisible by 9 (all of its digits have to add up to 9). Far faster for any clerk to calculate, and still not readily obvious to anyone not in the know - while this at least requires the clerk to know of the break-up of the algorithm, but if they do it is quite simple to check.

 

[rah]

The card readers had the equation so the clerk didn't manually calculate it. (only a few knew the actual calculation) It just wasn't connected on-line to a dB for an actual account check.

 

[Timsup2nothin]

Well, all credit card numbers use the luhn algorithm, though obviously not all numbers that do are real credit card ones
But yes, given the system has other ways of checking if the number is indeed a credit card, it does seem a bit redundant. Maybe at some past it was the core security measure for online checking (at least in the early internet, checking was done in stages, with the system taking some time to connect to a bank/do whatever to verify), but now is just one of many? Or, alternatively, maybe it started not as a safety measure but a way for the bank to generate the next free number more easily, but without having a more obvious/blatant sequence like for example simply adding +1 (?).

(as always, I just need this for a story - honest )

For story purposes...it doesn't really seem to have anything to do with generating the next free number. It's a checksum method, which as @rah said is more about error trapping. It catches your typo on the spot so it can be fixed before it goes further down the line.

 

[rah]

Very useful in old call centers that captured the CC number over the phone and then entered by hand by the operator.

 

[hobbsyoyo]

Monitoring coupled with guesswork. Little outbreaks due to mutated strains are happening all the time, not just in "flu season." So they monitor those and predict which strains are going to expand and cause problems vs which will just be beaten down without a whole lot of fuss, then they brew up the vaccine cocktail appropriately. Or so they hope. There's a whole lot in that process that can go wrong.

That's why health officials will frequently warn about the flu shot not being effective in a given year - they guessed wrong as to which strains would be prevalent and since they have to set up production months in advance, they can't really pivot to make a correction in time.

 

[Kyriakos]

The card readers had the equation so the clerk didn't manually calculate it. (only a few knew the actual calculation) It just wasn't connected on-line to a dB for an actual account check.

Would this mean that, back then, knowing this about cards would actually enable fraud? Or were there other safeguards as well when one was talking over the phone?

 

[rah]

Yes, knowing this about cards could assist in fraud. If talking to an existing customer there were other checks but not always followed. This was considered top secret back then. (not that it actually was)

 

[Narz]

Why don't more people drive scooters/mopeds? They're so awesome.

 

[Zkribbler]

Why don't more people drive scooters/mopeds? They're so awesome.

Rain? Large packages? Pets?

 

[Synobun]

They're difficult to insure (outright impossible, usually).

 

[Valka D'Ur]

Why don't more people drive scooters/mopeds? They're so awesome.

I used to have an avatar of a sunglasses-wearing potato who drove one. Spud was rather famous for awhile, even being made into a DYOS character (CivGeneral's gift to me one year ).

 

[Samson]

Why don't more people drive scooters/mopeds? They're so awesome.

Really high mortality rate as I understand it, compared to both cars and more powerful bikes. I feel that making them a better option for most peoples driving requirements would go a long way to a more sustainable way of living.

 

[The_J]

Also try to get on a highway with one of them...

 

[hobbsyoyo]

What do you call an area in a building that is filled with plants but is inaccessible? Like there is an area outside my apartment that has trees and shrubs and I'd call it a courtyard but it is completely inaccessible to anyone but grounds keepers.

 

[Synobun]

What do you call an area in a building that is filled with plants but is inaccessible? Like there is an area outside my apartment that has trees and shrubs and I'd call it a courtyard but it is completely inaccessible to anyone but grounds keepers.

A courtyard owned by rich people who hate the lower class?

 

[The_J]

What do you call an area in a building that is filled with plants but is inaccessible? Like there is an area outside my apartment that has trees and shrubs and I'd call it a courtyard but it is completely inaccessible to anyone but grounds keepers.

I'd normally call this an atrium, but wiki says I'm wrong about this .

 

[Arakhor]

Moderator Action: 100 posts have been moved to a new thread. Please remember that this is the thread for questions which aren't worth their own thread.