Last 4 as account finder
So, what are the odds if you call a bank and give the last 4 of your SS number that no other customer has it with:
100,000 customers
500,000 customers
1,000,000 customers
2,000,000 customers
4,000,000 customers
And what is the way to figure this? Stats class was a lifetime ago and I do not remember this kind of problem. I imagine it is done like the odds of 2 people having the same birthday in a group of 30 where you figure the odds of NOT having it and reverse it?
Quote: AZDuffmanI was dealing with a large USA bank this week. Instead of an account number they asked for the person's last 4. To my surprise this identified the person with no other info needed! The place has millions of customers.
WHAT?!
I don’t even think it’s unlikely for multiple customers to have the same last 4.
https://www.ssa.gov/history/ssn/geocard.html
Quote: gamerfreakWHAT?!
I don’t even think it’s unlikely for multiple customers to have the same last 4.
https://www.ssa.gov/history/ssn/geocard.html
That is my point, only 10,000 possible combinations assuming none are reserved (0000?) So many should have the same, but the one I called with (my job to call) they had to be the only one as Caller ID would not equate my number with one.
Quote: AZDuffmanI was dealing with a large USA bank this week. Instead of an account number they asked for the person's last 4. To my surprise this identified the person with no other info needed! The place has millions of customers.
So, what are the odds if you call a bank and give the last 4 of your SS number that no other customer has it with:
100,000 customers
500,000 customers
1,000,000 customers
2,000,000 customers
4,000,000 customers
And what is the way to figure this? Stats class was a lifetime ago and I do not remember this kind of problem. I imagine it is done like the odds of 2 people having the same birthday in a group of 30 where you figure the odds of NOT having it and reverse it?
They asked for NOTHING else?
Not for person name or birthday?
You just called and they said what is your last four digits of SSN and they suddenly knew who you were?
And we're you calling from your cell phone? This is important as many places will have cell info.
So you call from cell, it is recognized as belonging to you personally, they just ask your last four SSN to make sure it's not someone else using your phone
i can get your name by going through your trash
etc etc
Quote: darkozThey asked for NOTHING else?
Not for person name or birthday?
You just called and they said what is your last four digits of SSN and they suddenly knew who you were?
And we're you calling from your cell phone? This is important as many places will have cell info.
So you call from cell, it is recognized as belonging to you personally, they just ask your last four SSN to make sure it's not someone else using your phone
No, I explained above it was not mine, it was a client. So my phone would not match the number they had on file. Yes, I punched in the last 4 and they found the account on that alone. With a couple million customers I want to know how long the odds are.
Quote: AZDuffmanNo, I explained above it was not mine, it was a client. So my phone would not match the number they had on file. Yes, I punched in the last 4 and they found the account on that alone. With a couple million customers I want to know how long the odds are.
Could be if your last four returned multiple possibilities then they would have asked a follow-up.
You are correct that this is just the birthday match formula.
Quote: unJonCould be if your last four returned multiple possibilities then they would have asked a follow-up.
You are correct that this is just the birthday match formula.
This makes more sense.
Not sure why but I thought AZD was working at/with this bank in some professional capacity and knew they were only referencing account by last-4.
Quote: unJonCould be if your last four returned multiple possibilities then they would have asked a follow-up.
You are correct that this is just the birthday match formula.
Of course they would ask more, I have had them do so. This time there were none so means only 1 person had that last 4.
Quote: AZDuffmanOf course they would ask more, I have had them do so. This time there were none so means only 1 person had that last 4.
Well that’s a different a question and not the birthday problem. It’s the chance this particular person doesn’t have a last four as any of the other X people.
Chance = 1 - (9,999 / 10,000 )^X
. They have your phone number also, as I’m guessing you called them. So the odds of someone having your phone number and the same last 4 digits in Ss# is..... this doesn’t answer your question.... but they knew it was you via the phone number and was just checking by asking your last 4.... edit.... I think you are just forgetting a detail. Meaning.... perhaps you said a name or an account number or something else’s as well ...Quote: AZDuffmanI was dealing with a large USA bank this week. Instead of an account number they asked for the person's last 4. To my surprise this identified the person with no other info needed! The place has millions of customers.
So, what are the odds if you call a bank and give the last 4 of your SS number that no other customer has it with:
100,000 customers
500,000 customers
1,000,000 customers
2,000,000 customers
4,000,000 customers
And what is the way to figure this? Stats class was a lifetime ago and I do not remember this kind of problem. I imagine it is done like the odds of 2 people having the same birthday in a group of 30 where you figure the odds of NOT having it and reverse it?
Approximately zeroQuote: AZDuffmanSo, what are the odds if you call a bank and give the last 4 of your SS number that no other customer has it with:
1,000,000 customers
2,000,000 customers
4,000,000 customers
Quote: SOOPOO. They have your phone number also, as I’m guessing you called them. So the odds of someone having your phone number and the same last 4 digits in Ss# is..... this doesn’t answer your question.... but they knew it was you via the phone number and was just checking by asking your last 4.... edit.... I think you are just forgetting a detail. Meaning.... perhaps you said a name or an account number or something else’s as well ...
Again, it was NOT MY ACCOUNT. So they did not use Caller ID or anything else. This person was the only one with that last 4 as after I punched that in the automated system brought it up. I am aware they use Caller ID to screen as I have made easily 1,000 of these inquiries in my life. I am 100% certain that the last 4 was the only thing they used to identify.
True story:. When I was 19 I ordered from a Chinese takeout a "Half fried chicken and Pork Fried Rice".
The woman turned to the chef and yelled "Di Yi"
That was it!
I couldn't fathom that "Half Fried Chicken and Pork Fried Rice' translated to just "Di Yi" in Chinese and was certain she probably messed up my order so I questioned her rather suspiciously.
"Excuse me. 'Di Yi' is how you say 'half fried chicken and pork fried rice' in Chinese?'
"It means 'Number One'", and pointed to the menu!
Anyway, my point is be wary of trying to extrapolate what you think is going on with other people's systems of work.
Quote: darkozI suspect there is just some hidden automation using modern technology that allows them to identify with minimalist information.
Unless they are mind reading it is impossible. I am calling from another phone in another part of the country. And I call the same bank for multiple accounts.
Quote: AZDuffmanUnless they are mind reading it is impossible. I am calling from another phone in another part of the country. And I call the same bank for multiple accounts.
That's the genius of "hidden" automation.
You can't see it.
Just because you can't figure it out doesn't mean it's not there
Quote: AZDuffmanUnless they are mind reading it is impossible. I am calling from another phone in another part of the country. And I call the same bank for multiple accounts.
Voice recognition software?
Or maybe the FBI intercepted your call.
Quote: DRichIs it possible that the customer was in their system as having been tied to your company? Maybe he was the only customer with those last four that is cross referenced to your company?
Nope.
Quote: rxwineVoice recognition software?
Or maybe the FBI intercepted your call.
FBI is too buys following me in their Econolines to have time for that.
Quote: billryanIt's obviously magick.
You are closer to the answer than you intended
I dabbled in magic for awhile and the "hidden" solution to how the trick worked was usually so damn simple but almost no one ever guessed how I was doing it.
