# Luhn Algorithm or Modulus 10 Calculator

This online tool will calculate/validate the luhn digit number for any cards.

# Results...

Initial number:

**Step1 :** Starting with the second-to-last digit and moving to the left, double every second digit:

**Step2 :**If the result of the doubling is a two-digit number, add those 2 digits together:

**Step3 :**Now take the sum of all the digits:

Sum = (7 + 9 + 9 + 4 + 7 + 6 + 9 + 7 + 7 + 2 + 0) = 67

67 mod 10 =

1, that means this number is **Not Valid.**

**Info: **If you change the last digit from 0 to 3, the sum will be 70, and the number will be valid.

**What is Luhn-Algorithm**

The Luhn algorithm or Luhn formula is also known as **modulus 10** (or) **mod 10** algorithm.

This formula used to validate a variety of identification numbers.

**Example :**

Credit card numbers

Social Security Numbers (SSNs).

IMEI numbers

National Provider Identifier numbers

## Steps to calculate the luhn check digit:

Step 1) From the rightmost digit, which is the check digit, moving left, double the value of every second digit;

Step 2) If the product of this doubling operation is greater than 9, then sum the digits of the products or alternatively subtract 9 from the product.

Step 3) Take the sum of all the digits.

Step 4) Sum value Mod 10.

Step 5) Result = 1 , that means this number is Not Valid.

Result = 0 , that means this number is Valid.