The number of digits in a valid credit card can change depending upon the type of card. MasterCard and VISA use a 16 digit system, while others including American Express use a 15 digit system.
Most credit and debit cards have sixteen digits. American Express cards have fifteen. Even fifteen digits is enough to allow every single person on Earth to have over a thousand credit cards, which is why it's unlikely that a random string of digits will turn out to be a valid credit card number.
There are 16 digits in a Mastercard number, usually starting with 5.Mostly, they are just an account number. Some of the digits, however, are "check digits." That is, they come from some mathematical formula being applied to some of the other digits. That makes it near impossible to simply make up a string of 16 digits that are a valid credit card number. Of course, the location of the check digits and the formula which generates them are carefully guarded secrets.So, sorry, no example.
There are actually three valid answers: 17, 53, and 71 All are prime and all have digits adding to 8.
In order to know whether or not the credit card number is valid, one should check out from the bank of the credit card, or using the card at an ATM machine.
significant digits
Most credit and debit cards have sixteen digits. American Express cards have fifteen. Even fifteen digits is enough to allow every single person on Earth to have over a thousand credit cards, which is why it's unlikely that a random string of digits will turn out to be a valid credit card number.
All of them ! The whole number is used - plus other security features - to confirm the card is valid.
Mostly, they are just an account number. Some of the digits, however, are "check digits." That is, they come from some mathematical formula being appled to some of the other digits. That makes it near impossible to simply make up a string of 16 digits that are a valid credit card number. Of course, the location of the check digits and the formula which generates them are carefully guarded secrets.
There are 16 digits in a Mastercard number, usually starting with 5.Mostly, they are just an account number. Some of the digits, however, are "check digits." That is, they come from some mathematical formula being applied to some of the other digits. That makes it near impossible to simply make up a string of 16 digits that are a valid credit card number. Of course, the location of the check digits and the formula which generates them are carefully guarded secrets.So, sorry, no example.
"What if the credit card number isn't valid?"
There are actually three valid answers: 17, 53, and 71 All are prime and all have digits adding to 8.
In order to know whether or not the credit card number is valid, one should check out from the bank of the credit card, or using the card at an ATM machine.
A valid credit card number is a card that is recognized as real and usable. An invalid card is either expired or falsified.
significant digits
Significant Digits.
378 is not a valid octal number. Octal (base 8) uses digits 0-7.
A valid credit card number is a card that is recognized as real and usable. An invalid card is either expired or falsified.