You know that you are, nearly always, asked for the card number, off the front of your card, and the the 3 digit security number, from the back of the card.
It surprised me to find that the 3 security digits, from the back, are exactly the same as the third, fourth & fifth, from the left, in the front number.
This on all my cards.
I wonder, if it’s the same for everyone, why do they ask? Does it prevent forgery?
Maybe not the same for others!
You do know that everyone reading this will be checking? 
On my two debits and a credit card numbers do not match.
No matches on my cards … 
Yes, just checked with a neighbour & his 3 digit number is in his card number, but reversed.
Curiouser & Curiouser!
Still does not work for me.
The first 6 digits on a Credit Card are the bank identification number. The following numbers are personal identification numbers. So the CVV (3 numbers on the back, or 4 on the front, if you have an American Express card.) Should not be connected in any way to each other.
nothing like my CVV number
The numbers on the back bear no relation to those on the front of any of my cards.
OK, must be a coincidence with mine!
Yes, the CVV numbers are numbers used to verify that you own the card. If they matched the credit card number, then they would be useless since everyone would know what they were. Fraudsters would be able to tell just from the credit card number what the code was. They should not have any link to the credit card number except by coincidence.
I can see what you mean …
On the front I have, lets’ say …
xxxx…xxxx …xxxx …9999
One the reverse I have
9999 … xxx
So 9999 appears on both sides but on the reverse it is the 3 digit number that provides the extra level of security, that is invariably asked for on online purchases or transactions.
I have a debit and a credit card, both the same.
Definitely not the case on my cards, not even close. Don’t the sixteen digits identify the issuer, bank and account?
For example the first digit for my Visa cards is 4 and all my Master cards start with 5
The expiry date has a mathematical relationship with the card number but I don’t know how, that is the first level of security
The numbers on my cards don’t match either.
Not on mine. Any of them.
No, that’s not the case with my cards
