Credit Card Number Validator
What the Luhn check does — and doesn't — prove
The Luhn algorithm (also called the "mod 10" check) is a simple checksum built into real card numbers so a single mistyped or transposed digit gets caught immediately, before a charge is even attempted. Passing this check only means the number is well-formed — it does not mean the card exists, is active, or has funds. The card network shown (Visa, Mastercard, Amex, Discover) is a guess based on the number's prefix and length, not a verified lookup against a real issuer database.
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Numbers & CS
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Date & Time
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