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Luhn Algorithm Validator
Validate credit cards, IMEI, and other numbers using the Luhn (mod 10) checksum
Validate Number
Enter a number to validate
Step-by-Step Calculation
Starting from the rightmost digit, double every second digit. If the doubled value is > 9, subtract 9. Sum all digits. Valid if sum mod 10 = 0.
Generate Check Digit
Enter a partial number and we'll compute the Luhn check digit to append.
Enter a partial number above