A credit card is a
payment card issued to users (cardholders) as a method of payment.
It allows
the cardholder to pay for goods and services based on the holder's promise to
pay for them.
The issuer of the card (usually a bank) creates a revolving
account and grants a line of credit to the cardholder, from which the
cardholder can borrow money for payment to a merchant or as a cash advance.
Visa and MasterCard
are the two most prominent payment processors for credit cards.
Check your credit card number
- We'll check your number against the Luhn Algorithm to see if it is a valid credit card number.
- The first digit of a credit card number represent the category of entity which issued the card.
- The first six digits of a card number identify the institution that issued the card to the card holder.
- Digits 7 to final number minus 1 (the last is the checksum) indicate the individual account identifier.
- Last 4 digit is Check Digit
How to validate a Credit Card Number?
Most credit card
number can be validated using the Luhn algorithm, which is more or a less a
glorified Modulo 10 formula!
The Luhn Formula:
Drop the last digit
from the number. The last digit is what we want to check against
Reverse the numbers
Multiply the digits in
odd positions (1, 3, 5, etc.) by 2 and subtract 9 to all any result higher than
9
Add all the numbers
together
The check digit (the
last number of the card) is the amount that you would need to add to get a
multiple of 10 (Modulo 10)
Luhn Example:
| Step | Total | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Original Number: | 4 | 5 | 5 | 6 | 7 | 3 | 7 | 5 | 8 | 6 | 8 | 9 | 9 | 8 | 5 | 5 | |
| Drop the last digit: | 4 | 5 | 5 | 6 | 7 | 3 | 7 | 5 | 8 | 6 | 8 | 9 | 9 | 8 | 5 | ||
| Reverse the digits: | 5 | 8 | 9 | 9 | 8 | 6 | 8 | 5 | 7 | 3 | 7 | 6 | 5 | 5 | 4 | ||
| Multiple odd digits by 2: | 10 | 8 | 18 | 9 | 16 | 6 | 16 | 5 | 14 | 3 | 14 | 6 | 10 | 5 | 8 | ||
| Subtract 9 to numbers over 9: | 1 | 8 | 9 | 9 | 7 | 6 | 7 | 5 | 5 | 3 | 5 | 6 | 1 | 5 | 8 | ||
| Add all numbers: | 1 | 8 | 9 | 9 | 7 | 6 | 7 | 5 | 5 | 3 | 5 | 6 | 1 | 5 | 8 | 85 | |
| Mod 10: | 85 modulo 10 = 5 (last digit of card) | ||||||||||||||||
Credit Card Type
|
Credit Card Number
|
American Express
|
378282246310005
|
American Express
|
371449635398431
|
American Express Corporate
|
378734493671000
|
Australian BankCard
|
5610591081018250
|
Diners Club
|
30569309025904
|
Diners Club
|
38520000023237
|
Discover
|
6011111111111117
|
Discover
|
6011000990139424
|
JCB
|
3530111333300000
|
JCB
|
3566002020360505
|
MasterCard
|
5555555555554444
|
MasterCard
|
5105105105105100
|
Visa
|
4111111111111111
|
Visa
|
4012888888881881
|
Visa
|
4222222222222
Note
: Even though this number has a different character count than
the other test numbers, it is the correct and functional number.
|
Processor-specific Cards
|
|
Dankort (PBS)
|
76009244561
|
Dankort (PBS)
|
5019717010103742
|
Switch/Solo (Paymentech)
|
6331101999990016
|