### MOD 10

Luhn algorithm is a simple formula that is used to validate a set of numbers. These numbers may include credit card, IMEI numbers, and government numbers among others. This formula was created by a scientist, Hans Peter Luhn. Currently, it is being used widely. Its aim was to protect against accidental errors that might occur and not malicious damage created by individuals. Most government identification numbers and credit cards use it to identify the numbers that might have been misread or mistyped. The verification is against a verified check digit.

During verification, the last digit of the numbers is called a check sum number. All the other digits are used to verify the credit card company, the financial institution that issued the card or the customer’s number. Every company has a particular coding scheme that is totally different from another company. For you to generate the last digit, you need to perform a set of calculations against all the other set of digits. Apparently, you can use the Luhn algorithm to verify almost all credit cards. If you do this, you will be able to note the number that matches the check sum number.

Most credit card numbers can be validated using Luhn algorithm which uses more of less glorified modulo 10 formula first step is to drop the last digit since this is what you will be checking against. Next, you reverse the numbers that are there. This, you follow by multiplying the digits in odd positions by 2 and subtract to all or any result that is more than 9. The next step is to add all the numbers together then you check the digit which is the last number. Briefly, even if a number passes the test, it does not mean that it is totally valid but rather other test should be performed on the same. These may include checking the total number of digits among others. Otherwise, Luhn Algorithm has been known to be very accurate.