![]() Yes, even the shape and the substance of the card itself. The Four Major Credit Card Networks: A Brief HistoryĪ credit card is more than a rectangular slip of plastic and metal. How? It all goes back to when the credit card industry was struggling to get customers. Most importantly, the technology behind the number helps prevent fraud, minimizes payment issues and reduces errors. The order of the digits isn’t random but strategically organized, following an international standard.įrom that sequence, you can find out the issuing bank, your account number and more. That lengthy number on the front of your card is packed with crucial information. However, using this quick checksum algorithm goes a long way in catching unintentional errors that might otherwise lead to accidently charging the wrong card.Have you ever wondered what all those numbers you can never quite memorize stamped across your credit card actually mean? We use our cards daily but most of us have little understanding of the history and objectives they represent. Partly because the Luhn algorithm is not perfect, online stores also ask for the the card’s expiration date and the card verification number. Can you think of the other two twin errors that would slip though the test? Transposing 90 to get 09, or typing 22 instead of 55 (know as a “twin error”) are two possible errors that would pass the test of the Luhn algorithm. There are a few possible errors that would still result in a sum that is divisible by ten. Indeed, 70/10 has a remainder of zero!ĭoes a sum that is a multiple of ten guarantee that the user entered the correct number? No. Taking the sum of the digits in the bottom row, we get 7 + 9 + 9 + 4 + 7 + 6 + 9 + 7 + 7 + 2 + 3 = 70. If we go through the same algorithm with the correct card number we get the following result: Original number This alerts the computer that the number entered could not possibly be a valid card number. However if we divide 71 by 10, the remainder is one. In order for the computer to believe that the number entered could be valid, this sum must be divisible by ten (with a remainder of zero). If the result of doubling a digit is a two digit number (such as 18, 14, and 16 above), replace the result with the sum of the digits (1 + 8, 1 + 4, and 1 + 6). The original number (typed incorrectly): 7 ![]() How does this algorithm work? First it takes every other digit that is entered and doubles it. Thanks to the Luhn algorithm, the computer immediately gives the user an error message, even before asking for the expiration date and three digit card verification value. However, the shopper gets distracted when entering the card number, and transposes the 2 and 7, typing the following incorrect number: 799 72398713. Imagine the scenario following:Ī well-intentioned shopper has a credit card with the following number: 79927398713 (this number is made up as we wouldn’t want to publish a real credit card number). And this particular checksum was created by a computer scientist and avid inventor by the name of Hans Peter Luhn in 1954 (patented in 1960). As the name implies, a checksum involves a relatively quick check involving the sum of the digits on the card. The Luhn Algorithm is one of many checksum algorithms. The algorithm is known as the Luhn Algorithm. With all the online transactions that happen every day, accidents like this must happen all the time right? Actually, there is a clever algorithm that prevents almost all such accidents. Maybe that mistyped number belongs to one of your parent’s cards, and the person who typed it just accidently charged $600.00 to their account. With all the credit card numbers that exist in the world, perhaps there is one that actually corresponds to this mistyped number. Imagine entering a credit card number into an online store and due to the slip of a finger, midway through typing the number, one enters 72 instead of 27. And sometimes the person typing might make a mistake. But when those card-reading devices fail, or when we make purchases online, a person actually types the card number into the computer. At stores and restaurants, the cards are typically swept through a small electronic device or their chip is inserted. How can you tell if a credit card number is valid or invalid? Meet the Luhn algorithm, one of many checksums helping us keep the internet in order.Ĭredit and debit cards are used in approximately 75% of transactions in the United States. Twitter Lists for Programming and Computer Science.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |