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rated:
I saw this on another forum and thought I'd share:

Write a fake pin number on the back of your credit card. That way if it gets stolen the person will only get 3 attempts before the ATM machine swallows the card. 

Use numbers like 1, 6, 9 and 0, numbers that can be turned upside down, and write it sideways along the side edge of the card, so the person won't know which way is up. That way he eats up his attempts.
 

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Most Recent Posts
.33 isn't 1/3. Woooow. You've been debunked like three separate ways on this thread.

And, yes, I understand probability. ... (more)

bppcomplete (Feb. 12, 2017 @ 10:33a) |

If your credit card is stolen and the thief has not skimmed/video recorded your PIN, they will not go to an ATM to rando... (more)

Shandril (Feb. 16, 2017 @ 11:11a) |

But it's so simple. All I have to do is divine from what I know of you: are you the sort of man who would put his pin on... (more)

adamc (Feb. 21, 2017 @ 12:43p) |

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rated:
This is right up there with the "CID" crowd. I don't care if someone gets cash advances from ATMs or buys gold jewelry for it's melt resale value. I rely on Reg Z and Zero liability to protect me.

Any card issuer dealing with me should know from their fraud algorithms that I don't make cash advances and should be blocking the transaction forcing me to call them.

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This is one of the nicer features of Citi Credit Cards, the ability to disable the cash advance PIN.  I wish other CC companies offered that ability.

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I don't think the intention is to keep thieves from getting a cash advance as much as tricking the thief into losing the card into the ATM.
But yeah, If my card is lost I report it, and the charges are waived. No need to use weird tricks to avoid unlawful charges.


Might make more sense on a debit card where they can get to my actual cash directly.

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Definitely doesn't look sketchy when you hand someone a card that you've written numbers in random places either.

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tedteddy said:   I saw this on another forum and thought I'd share:

Write a fake pin number on the back of your credit card. 

  Is this what FW is coming to? Copying and pasting reddit tips? How about not writing ANY number at all on your card? DUH!

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tedteddy said:   I saw this on another forum and thought I'd share:

Write a fake pin number on the back of your credit card. That way if it gets stolen the person will only get 3 attempts before the ATM machine swallows the card. 

Use numbers like 1, 6, 9 and 0, numbers that can be turned upside down, and write it sideways along the side edge of the card, so the person won't know which way is up. That way he eats up his attempts.

  What a ridiculous idea. Why bother writing any number at all? Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries? Why bother trying to mislead them? It's a waste of ink, if nothing else.
This belongs in the tinfoil hat category.

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What's wrong with reporting your card lost or stolen?

Since most cards are chip and signature, your average bad guy will test it at a gas pump with a small purchase. If it works, they're off to Beat Butt to stock up on some giant flat screen TVs.

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canoeguy1 said:   
Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries?


3 in 10000? 😜

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Chyvan said:   This is right up there with the "CID" crowd. I don't care if someone gets cash advances from ATMs or buys gold jewelry for it's melt resale value. I rely on Reg Z and Zero liability to protect me.

Any card issuer dealing with me should know from their fraud algorithms that I don't make cash advances and should be blocking the transaction forcing me to call them.


Zero Liability?

ATM fraud liability is dependent on when you report the card stolen. If they manage to use the card before you report it stolen you could be on the hook for $50, $500, or the whole thing.

source:

https://www.consumer.ftc.gov/articles/0213-lost-or-stolen-credit-atm-and-debit-cards#Limit

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canoeguy1 said:   
tedteddy said:   I saw this on another forum and thought I'd share:

Write a fake pin number on the back of your credit card. That way if it gets stolen the person will only get 3 attempts before the ATM machine swallows the card. 

Use numbers like 1, 6, 9 and 0, numbers that can be turned upside down, and write it sideways along the side edge of the card, so the person won't know which way is up. That way he eats up his attempts.

  What a ridiculous idea. Why bother writing any number at all? Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries? Why bother trying to mislead them? It's a waste of ink, if nothing else.
This belongs in the tinfoil hat category.

  As previously mentioned, the purpose is to bait the thief into attempting to use it for a cash withdrawal, which he otherwise wouldnt do if he didnt think he had the PIN, then the ATM eats the card after a couple failed PIN entries and removes your card from play.  It's a rather clever trick in theory, but in practice it's way too over-clever and serves very little purpose - it's kind of on the same level as writing your actual PIN on your card since, you know, no thief would believe anyone would be dumb enough to write their actual PIN on their card... 

 

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Glitch99 said:   
canoeguy1 said:   
tedteddy said:   I saw this on another forum and thought I'd share:

Write a fake pin number on the back of your credit card. That way if it gets stolen the person will only get 3 attempts before the ATM machine swallows the card. 

Use numbers like 1, 6, 9 and 0, numbers that can be turned upside down, and write it sideways along the side edge of the card, so the person won't know which way is up. That way he eats up his attempts.

  What a ridiculous idea. Why bother writing any number at all? Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries? Why bother trying to mislead them? It's a waste of ink, if nothing else.
This belongs in the tinfoil hat category.

  As previously mentioned, the purpose is to bail the thief into attempting to use it for a cash withdrawal, then the ATM eats the card after a couple failed PIN entries.  It's a rather clever trick in theory, but in practice it's way too over-clever and serves very little purpose - it's kind of on the same level as writing your actual PIN on your card since, you know, no thief would believe anyone would be dumb enough to write their actual PIN on their card... 
 

I've seen tons of people write their a

rated:
Some insane number of people have password123 as their login.

Yet many of those same people will follow this advice to reduce risk. It's not necessarily a bad idea, but it's like driving over dollars to pick up pennies.

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frankm said:   canoeguy1 said:   
Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries?

3 in 10000? 😜


3 in 10000 only if they are dumb enough to select the same pin multiple times. Otherwise, the odds are slightly better 1/10000 + 1/9999 + 1/9998.

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Thieves would rather have cash than goods. Thinking they can get cash because of the written PIN & assuming they fail 3 times so the card gets eaten.

Then there'll be absolutely no hassle if the CC issuer or merchants challenge charges for goods & services.

A written PIN will increase the odds thieves to try for cash rather than goods & services.

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zapjb said:   Thieves would rather have cash than goods. Thinking they can get cash because of the written PIN & assuming they fail 3 times so the card gets eaten.

Then there'll be absolutely no hassle if the CC issuer or merchants challenge charges for goods & services.

A written PIN will increase the odds thieves to try for cash rather than goods & services.

  The thief knows very well that he would lose the card after the third try. So he would stop at 2 tries, and keep the card.

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zapjb said:   Thieves would rather have cash than goods. Thinking they can get cash because of the written PIN & assuming they fail 3 times so the card gets eaten.

Then there'll be absolutely no hassle if the CC issuer or merchants challenge charges for goods & services.

A written PIN will increase the odds thieves to try for cash rather than goods & services.

  wrong PIN = risk of CC freeze (especially if it lacks a history of cash advances). much lower risk = head to a Best Buy (close to where cardholder lives) and buy an Ipad.  unload it for 50-70% of market price in some other jurisdiction. rinse and repeat.

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byex0039 said:   
frankm said:   
canoeguy1 said:   
Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries?

3 in 10000? 😜


3 in 10000 only if they are dumb enough to select the same pin multiple times. Otherwise, the odds are slightly better 1/10000 + 1/9999 + 1/9998.

  
So you're telling me there's a chance???

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Ease up on the OP. i write the last 4 digits of my acct # on the back of the card so i can tell which debit card is for which account. i've never had one stolen or lost, but once it kept my klepto 'better half' from draining my account. next time i tried to use it i was locked out and had to call in and reset. mentioned it in passing to wife and she admitted to blowing up the pin trying to use the digits i wrote on the back. lol, i guess.

so this technique worked for me, but the crook has to be a real idiot or an unseasoned opportunist.

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Well, since I can't remember anything.. I do put my PIN on the back of the ATM card as a cypher.

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Write your passwords and pins in binary and them just translate them back when you have to enter them. This cypher will trick both humans and computers.

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so, a certain so called leader of the free world:

1010011010 1010011010 1010011010

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byex0039 said:   
frankm said:   
canoeguy1 said:   
Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries?

3 in 10000? 😜


3 in 10000 only if they are dumb enough to select the same pin multiple times. Otherwise, the odds are slightly better 1/10000 + 1/9999 + 1/9998.

huh??  People are bad at math around here.  So if the pin had to be between 1 and 4 and you had 3 guesses, would your chances be 3/4 or 1/4+1/3+1/2?  (hint: that adds up to > 1).

rated:
frankm said:   
Chyvan said:   This is right up there with the "CID" crowd. I don't care if someone gets cash advances from ATMs or buys gold jewelry for it's melt resale value. I rely on Reg Z and Zero liability to protect me.

Any card issuer dealing with me should know from their fraud algorithms that I don't make cash advances and should be blocking the transaction forcing me to call them.


Zero Liability?

ATM fraud liability is dependent on when you report the card stolen. If they manage to use the card before you report it stolen you could be on the hook for $50, $500, or the whole thing.

source:

https://www.consumer.ftc.gov/articles/0213-lost-or-stolen-credit...
 

  Clearly the comment was towards the use of CCs and not DCs.

rated:
MDfive21 said:   Ease up on the OP. i write the last 4 digits of my acct # on the back of the card so i can tell which debit card is for which account. i've never had one stolen or lost, but once it kept my klepto 'better half' from draining my account. next time i tried to use it i was locked out and had to call in and reset. mentioned it in passing to wife and she admitted to blowing up the pin trying to use the digits i wrote on the back. lol, i guess.

so this technique worked for me, but the crook has to be a real idiot or an unseasoned opportunist.

  What would happened had you not wrote anything?

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frankm said:   dependent on when you report the card stolen.

You're full of crap. It's dependent on when you DISCOVER the loss of your card. If you delay reporting after you know it's missing, only then do you get hit with the higher liability.

https://www.consumer.ftc.gov/articles/0218-electronic-banking#lost

"If you report the loss within two business days after you realize your card is missing, you won't be responsible for more than $50 of unauthorized use."

rated:
libralibra said:   
byex0039 said:   
frankm said:   
canoeguy1 said:   
Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries?

3 in 10000? 😜


3 in 10000 only if they are dumb enough to select the same pin multiple times. Otherwise, the odds are slightly better 1/10000 + 1/9999 + 1/9998.

huh??  People are bad at math around here.  So if the pin had to be between 1 and 4 and you had 3 guesses, would your chances be 3/4 or 1/4+1/3+1/2?  (hint: that adds up to > 1).

Close, but also not correct. I wouldn't judge people's math skills quite so fast.

Use probability of two independent events occurring (since each attempt is independent of the one before it-there is no "memory" of the first attempt that would affect the second or third attempt)
P(A or B)=P(A)+P(B)- P(A AND B)

Thus, for the first two events:
P(A or B) = 1/4+1/3-(.25*.33) 
= 0.4975

Now add the third event:
P=0.4975+1/2-(.4975*.5)
=0.74875

ie just under 3/4.

BTW: My original 3/10000 quote was just a quick answer. I don't think it matters much whether it's 0.03% or a few decimal points more...

rated:
Would there be an advantage to "encouraging" the bad guy to try your CC/DC at an ATM by having a fake PIN written on the card, since those machines record an image of the user's face?

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canoeguy1 said:   Thus, for the first two events:
P(A or B) = 1/4+1/3-(.25*.33) 
= 0.4975

  
Dude this is exactly 2/4 = 1/2; you made a rounding mistake; 1/4 * 1/3 = 1/12; don't simplify to .0825 (??).

People *are* remarkably bad at math around here... the probability of selecting 3 things out of 10,000 with one of them correct is exactly 3/10000 if you choose 3 distinct items. It is slightly worse (1 - (9999/10000)^3) if you choose them uniformly at random, but not enough to matter (3e-8; you can also estimate this with the first-order Taylor expansion).

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wilesmt said:   Some insane number of people have password123 as their login.

No so much anymore. http://www.pcworld.com/article/2872303/success-hardly-anyone-use...

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rated:
I write "Stolen - Pick Up Card" on the ID strip. That way if it ever gets stolen it is already tagged and makes it much harder for them to use it.
The merchant will hold the card and contact the issuer, no hassle for me that way/

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vipercon said:   I write "Stolen - Pick Up Card" on the ID strip. That way if it ever gets stolen it is already tagged and makes it much harder for them to use it.
The merchant will hold the card and contact the issuer, no hassle for me that way/

  No hassle for you? What about whenever YOU use it?

rated:
austex said:   Would there be an advantage to "encouraging" the bad guy to try your CC/DC at an ATM by having a fake PIN written on the card, since those machines record an image of the user's face?
  it would record some guy wearing a hoodie, with some of it covering a part of his face not covered by sunglasses.

that'll do a lot of good.

rated:
bppcomplete said:   
canoeguy1 said:   Thus, for the first two events:
P(A or B) = 1/4+1/3-(.25*.33) 
= 0.4975

  
Dude this is exactly 2/4 = 1/2; you made a rounding mistake; 1/4 * 1/3 = 1/12; don't simplify to .0825 (??).

People *are* remarkably bad at math around here... the probability of selecting 3 things out of 10,000 with one of them correct is exactly 3/10000 if you choose 3 distinct items. It is slightly worse (1 - (9999/10000)^3) if you choose them uniformly at random, but not enough to matter (3e-8; you can also estimate this with the first-order Taylor expansion).

  Buddy, no rounding mistake. Done with a calculator. Try it before you post.
And no, it's not 3/10000 since you won't retry the same pin on the second try that you KNOW failed on the first try. Thus, on the second try, there are only 9999 numbers to choose from.
If you don't understand probability (and you clearly don't-you're just blowing hot air), try not to throw insults (in fact, you shouldn't throw insults even if you did know more than others). 

rated:
yep, the answers are definitely 3/4 and 3/10000 - people can think of it this way: there's no difference between grabbing 3 balls from a pit of 10000 balls all at once or one-by-one, the odds are still 3/10000 to get the single winner.

Sorry about the phrasing before. I was just shocked at how much green the wrong answer was getting. Probably no one stopped to think it thru, but at first glance you just know that the summation looks fishy. Couple that with a recent thread where a poster just handwaved a bunch of numbers to come up with the wrong answer for the break even point on an Andrews CD and I just think, "Isn't this supposed to be a finance forum?"

btw, I'm not entirely sure that formula with the P(A and B) is really the right one to use in this case. I.e. P(A and B) = 0 since you can't have 2 pins. I think it describes a completely different problem that just happens to come up with the same answer as this one.

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libralibra said:   yep, the answers are definitely 3/4 and 3/10000 - people can think of it this way: there's no difference between grabbing 3 balls from a pit of 10000 balls all at once or one-by-one, the odds are still 3/10000 to get the single winner.

Sorry about the phrasing before. I was just shocked at how much green the wrong answer was getting. Probably no one stopped to think it thru, but at first glance you just know that the summation looks fishy. Couple that with a recent thread where a poster just handwaved a bunch of numbers to come up with the wrong answer for the break even point on an Andrews CD and I just think, "Isn't this supposed to be a finance forum?"

btw, I'm not entirely sure that formula with the P(A and B) is really the right one to use in this case. I.e. P(A and B) = 0 since you can't have 2 pins. I think it describes a completely different problem that just happens to come up with the same answer as this one.

  It's only 3/10000 if you put the ball back before trying again. You would then have a pool of 10000 balls again for the second try.

Similarly, with the PIN, it's only 3/10000 if you allow yourself to pick any PIN on try 2, INCLUDING the PIN that you already know failed. That doesn't make sense, though. You know it failed, so you would remove it from the pool of numbers. Therefore, on Try 2, there are only 9999 possibilities.

BTW: A and B refers to Try 1 and Try 2, not different PINS. P (A and B) is not zero, since there is a finite chance on each try of getting the PIN right. In fact, you could get it right on both tries by picking the same PIN. Thus, P(A and B) is the chance of getting both tries right. Of course, this assumes you keep trying even if you guess the correct number on Try 1 (or Try 2). 

rated:
vipercon said:   I write "Stolen - Pick Up Card" on the ID strip. That way if it ever gets stolen it is already tagged and makes it much harder for them to use it.
The merchant will hold the card and contact the issuer, no hassle for me that way/

  Please God allow me to hold my tongue back on this........

rated:
I like how this turned into a grade-school math thread.

Skipping 10 Messages...
rated:
Glitch99 said:   
canoeguy1 said:   
tedteddy said:   I saw this on another forum and thought I'd share:

Write a fake pin number on the back of your credit card. That way if it gets stolen the person will only get 3 attempts before the ATM machine swallows the card. 

Use numbers like 1, 6, 9 and 0, numbers that can be turned upside down, and write it sideways along the side edge of the card, so the person won't know which way is up. That way he eats up his attempts.

  What a ridiculous idea. Why bother writing any number at all? Your PIN is four digits, so 10,000 possible combinations. What are the chances of someone guessing the correct combination within three tries? Why bother trying to mislead them? It's a waste of ink, if nothing else.
This belongs in the tinfoil hat category.

  As previously mentioned, the purpose is to bait the thief into attempting to use it for a cash withdrawal, which he otherwise wouldnt do if he didnt think he had the PIN, then the ATM eats the card after a couple failed PIN entries and removes your card from play.  It's a rather clever trick in theory, but in practice it's way too over-clever and serves very little purpose - it's kind of on the same level as writing your actual PIN on your card since, you know, no thief would believe anyone would be dumb enough to write their actual PIN on their card... 

 


But it's so simple. All I have to do is divine from what I know of you: are you the sort of man who would put his pin onto his own credit card or his enemy's? Now, a clever man would put the pin onto his own credit, because he would know that only a great fool would key in what he was given. I am not a great fool, so I can clearly not choose the pin in front of you. But you must have known I was not a great fool, you would have counted on it, so I can clearly not choose the pin in front of me.

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